Methods for treating abnormal growths in the body using a flow reducing implant

RELATED APPLICATIONS

0001This application is a continuation of U.S. application Ser. No. 10/491,976 filed on Oct. 8, 2004 (now abandoned), filed as PCT application No. PCT/IL2002/000805 on Oct. 3, 2002, which designates the U.S. and which published in English, which is a continuation-in-part of PCT application No. PCT/IL2001/000284 filed on Mar. 27, 2001, which designates the U.S. and which published in English, which is a continuation-in-part of U.S. application Ser. No. 09/534,968 filed Mar. 27, 2000, the technical disclosure of all of which are incorporated herein by reference. This application also claims the priority of Israel application Nos. 145750 filed Oct. 4, 2001 and 151162 filed Aug. 8, 2002, the technical disclosure of all of which are incorporated herein by reference.

FIELD OF THE INVENTION

0002The present invention relates to implants for reducing flow through bodily conduits, for example, blood vessels.

BACKGROUND OF TAE INVENTION

0003The heart pumps blood through the body. The heart itself is fed by coronary arteries that end at capillaries. The capillaries are drained by a network of coronary veins, that (typically) flow into a vein known as the coronary sinus. The coronary sinus is a short, large diameter vein that is substantially contiguous with a right atrium, the atrium that collects all venous blood from the body.

0004Occlusion of coronary arteries is a leading cause of death, especially sudden death, in what is commonly called a “heart attack”. When blood flow to a portion of the heart is suddenly stopped, the portion becomes ischemic and its electrical activity is disrupted. As the activity of the heart is mediated by electrical signal propagation, such disruption typically propagates to the rest of the heart, disorganizes the heart's activation and causes the heart output to be reduced drastically, which leads to ischemia and death of the brain. In addition, the disorganized activity often damages the heart beyond what was caused directly by the blockage.

0005If a patient survives the direct effects of the heart attack, the damage to the heart may predispose the patient to future electrical disorders and/or may significantly reduce the cardiac output, thus reducing quality of life and life expectancy.

0006Angina pectoris is a chronic or semi-chronic condition that, while not life-threatening, significantly reduces quality of life. In general, the heart responds to increased demand by working harder, requiring more coronary blood flow. When coronary arteries are stenosed or occluded, the increased blood flow cannot be provided, and pain, caused by the resulting ischemia, is produced.

0007The heart has natural mechanisms to overcome stenosis in coronary arteries. One such mechanism is angiogenesis, in which new arteries are created, for bypassing the stenosis.

0008Since angiogenesis sometimes does not occur naturally, various procedures have been suggested to encourage it. For example Trans-Myocardial Revascularization (TMR), is a process in which multiple holes are drilled in the heart, with the intent of causing new vessels to be created.

0009Beck, in “The Surgical Management of Coronary Artery Disease: Background, Rationale, Clinical Experience” by C. S. Beck and B. L. Brofman, 1956, by the American College of Physicians in Annals of Internal Medicine Vol. 45, No. 6, December 1956 and in “Long Term Influence of the Beck Operation for Coronary Heart Disease”, by B. L. Brofman in the American Journal of Cardiology August 1960, the disclosures of which are incorporated herein by reference, performed open chest surgery in which a coronary sinus vein was restricted, by an external suture. After a few months, coronary blood supply apparently improved. However, this method has fallen in disfavor, in part possibly due to the need to open the chest and lift up the heart, to reach the coronary sinus vein.

0010A standard treatment of stenosed arteries is inserting a stent into the artery, at the stenosed point. The stent, for example a metal coil or mesh, is expanded to have an inner diameter similar to that of the original stenosed blood vessel. If many and/or elongated stenoses are present, it is not common to implant multiple stents. Instead, a bypass procedure, in which a conduit is used to bypass the stenoses, is performed.

0011U.S. Pat. No. 5,618,301, the disclosure of which is incorporated herein by reference, describes a stent-like device for reducing the diameter of a body conduit. What is described is an open mesh stent that can be inserted in a channel created by a TIPS (Trans-Jugular Intra-Hepatic Portal-Systemic Shunt) procedure, to reduce the blood flow rate through the channel, In order to ensure the flow diameter is reduced and prevent flow through the open mesh, a plurality of thromobogentic threads are provided on the outside of the mesh. However, as can be appreciated, intentionally forming thrombosis in most any part of the vascular system, and especially near the heart, can lead to propagating coagulation or floating thromboses, which are potentially fatal.

SUMMARY OF THE INVENTION

0012An aspect of some embodiments of the invention relates to an anchor for a flow reducing implants adapted for insertion into a blood vessel. In an exemplary embodiment of the invention, one or more tabs are provided on a circumference of the reducing implant. In an exemplary embodiment of the invention, these tabs engage the blood vessel wall if the implant moves axially relative to the blood vessel and are, for example, extended axially towards or away from the reducing implant. Alternatively or additionally, these tabs prevent rotational motion. In some embodiments of the invention, the tabs are not exactly aligned with the axis of the blood vessel, for example, being pointed towards the wall of the blood vessel or being angled relative to the axis, but in the plane of the blood vessel wall. In an exemplary embodiment of the invention, the tabs are elastically pre-stressed to extend in the desired direction. Alternatively, the tabs are formed out of a same sheet material as the reducing implant. and the implant is of a type where one portion is narrowed and another is flared. The tabs are attached to the flared portion and cut away from the narrowed portion, so that when the reducing implant is deployed the tabs continue in a same plane as the flared portion.

0013Optionally, the tabs dig into the blood vessel wall and/or are adapted to encourage tissue ingrowth or other biological or physical anchoring effects.

0014An aspect of some embodiments of the invention relates to varying slit geometry in a reducing implant to effect a control over the expanded shape of the reducer. In an exemplary embodiment, a slit-type flow reducing implant comprises a matrix, for example a sheet of metal into which one or more slits are cut. The one or more slits serve to govern the contour of an expanded configuration of the slit-type flow reducing implant. In an exemplary embodiment, the slit-type reducing implant is delivered to the implantation site in a contracted size, for example within a delivery sheath, and expanded to is final configuration at the deployment site. Said expansion, for example, employs the use of a balloon expansion catheter, for example, that exerts appropriate expansion force on the walls of the lumen of the flow reducing implant so that the slits expand and the implant attains its final configuration.

0015In an exemplary embodiment of the invention, the one or more narrowed sections are non-expandable, expand less and/or require a greater force to cause them to expand, as compared to flared sections. In this manner, using expansion force provided by a standard balloon catheter that expands within the lumen of the flow reducing implant, the implant achieves its final configuration comprising at least one flared section and at least one narrowed section.

0016Alternatively or additionally, at least a portion the flow reducing implant is self expanding (e.g., shape-memory, elastic or super elastic). Optionally, the flow reducing implant comprises materials with a shape memory so the flow reducing implant automatically attains a desired shape following release, for example, from a delivery catheter into the coronary sinus.

0017In an exemplary embodiment of the invention, the flow reducing implant comprises a rim, for example along the flared edge, that is constructed to be more difficult to expand (for plastic) or expand less (for self-expanding) than portions of the flow reducing implant just inside the rim.

0018In an exemplary embodiment, the slits of the slit-type reducing implant can be varied in width, thickness (of surrounding material) density, length and/or orientation thereby providing specific expanded configurations to the implant (e.g., self-expanding or actively expanded). In this manner, flow reducing implants providing different configurations, for example, filling the flow reduction needs of a variety of environments in the body, can be provided. Alternatively or additionally, the variations may affect the order in which parts expand and/or the response to an external pressure, thus possibly allowing various effects to be achieved from a single reducing implant. Alternatively or additionally, the variations may affect the amount of blood flow through the reducer walls.

0019For example, one or more slits may be provided in the flared section of the flow reducing implant walls that are oriented transverse, oblique and/or longitudinal to the flow reducing implant flow passage. As a result, the flared section expands to a specific contour, for example, with a gradual slope, to fit a specific blood vessel and/or provide a spatial blood flow profile. Optionally, the slits governing the configuration of the flow reducing implant are arranged so that the implant achieves a configuration that is asymmetric.

0020In an exemplary embodiment, a flow reducing implant comprises a smooth edge along its rim, defined, for example by the pattern of slits. The smooth edge, for example, reduces irritation to the tissue, for example to venous tissue that is often more delicate than arterial walls.

0021In an exemplary embodiment, a mesh-type flow reducing implant comprises a woven open material, for example of metal and/or plastic fibers, using methods well known in the art.

0022In an exemplary embodiment, a mesh-type or woven flow reducing implant comprises a covering that restricts blood flow through the wall of the narrow area of the flow reducing implant while one or more portions of the flared sections are not covered. Optionally, at least one portion of one or more of the uncovered flared section is adapted to interface with the blood vessel wall, for example anchoring the implant in the blood vessel wall. Optionally, the flow reducing implant is coated with a flexible coating (inside and/or out) and/or defines a densely woven mesh pattern and/or slit pattern, that prevents or reduces blood flow through the flow reducing implant surface, for example, forcing at least 40%, 60%, 80%, 90% or any smaller, greater or intermediate flow percentage to be through an axial lumen defined by said flow reducing implant. In an exemplary embodiment of the invention, the dense mesh and/or dense slits fill at least 30%, 40%, 60%, 70%, 80% or any greater, smaller or intermediate percentage of a surface of the flow reducing implant.

0023Some features described for a woven mesh-type reducing implant may be applied to a slit-type reducing implant and embodiments described for a slit-type reducing implant may be applied to a mesh-type reducing implant. In addition, an aspect of some embodiments includes structural improvement that are less specific to the type of implant material.

0024In an exemplary embodiment of the invention, the reducer is formed of a thick material, possibly with a constant outer diameter, with the flared out portions being formed by thinning the inside layer of the reducer. The reducer may be, for example expanding or it may be simply crimped, so that it expands uniformly along its length, like a stmt. Alternatively or additionally, this structure is used to assist in differentiating the inner diameters of different parts of an expanding reducer.

0025An aspect of some embodiments of the invention relates to a flow reducing implant that may be modified following implantation in a blood vessel, for example a coronary sinus and/or artery. For example, such modifications may be made in the size of its flared and/or narrowed sections, shape or configuration and/or in situ location.

0026In an exemplary embodiment of the invention, the blood flow exiting a flow reducing implant is modified by inserting an insert into the narrow and/or flared sections of the flow reducing implant. In an exemplary embodiment of the invention, the inserted body comprises a funnel with a variable diameter, such diameter being determined by the diameter of surrounding implant. For example, as the in variable insert is pressed into a flared section with a gradual slope, the size of the funnel insert and/or hole at its apex, is reduced, thereby reducing the blood flow through the flow reducing implant.

0027Alternatively or additionally, the flow reducing implant includes a set of apertures on its narrow section and/or a set of hooks or other engagable elements adapted to be engaged by a catheter that is inserted into the reducer. The catheter engages the flow reducing implant and pulls in radially on the walls, for example, of the narrowed section, to reduce its diameter.

0028Alternatively or additionally, one or more rings or cords, is provided around some or all of the circumference of the narrowing (or other part of the reducer implant). These rings may prevent expansion. Alternatively or additionally, when sufficient pressure is applied, the rings (or cord) may tear and greater expansion (e.g., to the limits defined by the device or a next ring, under the applied pressure, are achieved). Alternatively or additionally, the ring is elastic and when sufficient pressure is applied, the implant expands plastically, until the point where the applied pressure is smaller than the sum of the resistance of the implant and the resistance of the ring. Once the pressure is removed, the force applied by the ring is not enough to collapse the implant, for example, due to the rigidity of the implant or due to the change in geometry of the implant.

0029Alternatively or additionally to providing multiple rings, each with a different breaking point, a belt with multiple stop points may be provided. For example, each time pressure is increased, the belt may jump one stop, thereby allowing some expansion of the narrowing. The stop points may, for example, offer equal or increasing resistance to jumping.

0030Optionally, when a cord is provided, it is weaved into the reducer implant, possibly serving to block flow through the implant wall additionally or alternatively to determining its geometry. Optionally, the length of cord can be varied by a physician, for example before implantation, or after, for example by engaging the cord and pulling it to reduce the reducing implant narrow diameter.

0031In some embodiments of the invention, the flow reducing implant wall at the narrowing is formed by overlapping scales (e.g., by “U” shaped cuts cut out of the implant wall). As the cord expands, the edges on the at least one wall of the cord-type flow reducing implant move in relation to each other, thereby providing one or more expansion diameters. In an exemplary embodiment of the invention, the original diameter of the narrowed section of the implant is greater than that of the deployed device. Providing such “U” shaped cuts (e.g., with the tongue of the “U” pointing perpendicular to the axis), allows the narrowed section to be compressed, whereby the “U” tongues overlap like scales, inside the lumen of the implant and/or outside of the lumen.

0032Alternatively or additionally, the implant may be formed of a rolled sheet material, with overlap. As the implant is expanded, the overlap between parts of the sheet is reduced. Optionally, the initial overlap is set by a cord.

0033In an exemplary embodiment, a plurality of rings are provided and are spaced axially apart from each other, limiting the expansion of the section between them. A plurality of such rings may also be used to define the expanded geometry to be other than a simple, symmetric narrowing. For example to define the slope of the narrowing.

0034In an exemplary embodiment of the invention, the ring is an inflatable balloon, for example mounted on the outside of the reducing implant or formed by the surfaces of the implant. In an exemplary embodiment of the invention, as the balloon is inflated more, the reducing implant inner diameter lessens. In an exemplary embodiment of the invention, the balloon is inflated outside the body. Alternatively or additionally, it is inflated during implantation. Alternatively or additionally, the balloon is inflated after the fact, for example by guiding a needle catheter to the implant, piecing the balloon with the needle and injecting a fluid through the needle. Optionally, the balloon is backed by a tough layer, for example kevlar to prevent over penetration of the needle. Alternatively or additionally, the needle catheter is shaped to match the narrowing geometry and thus ensure correct placement. Alternatively or additionally, the needle length is limited by a stop so it cannot penetrate far past the reducer implant wall.

0035Alternatively or additionally, to an inflated balloon, the balloon may be self inflating, for example being formed of (or filled with) a material that expands under moist conditions.

0036In an exemplary embodiment of the invention, the reducer is surrounded by an active band, for example including a motor which is activated by external signals (e.g., RF ultrasound or magnetic fields) to shorten or lengthen the effective length of the band.

0037Alternatively or additionally to providing a mechanism for changing a narrowing, other flow control methods may be used. In one example, one or more flaps or ribbons selectively extend into the lumen of the reducing implant. Such ribbons or flaps may be selectively torn and/or bent flat to the vessel wall, for example during or after deployment. Alternatively or additionally, the reducing implant may include two coaxial reducing implants, with slots that can be selectively aligned. If the slots are misalign, flow through the walls of the reducing implants is reduced. If the slots are aligned, such flow is increased. The reducing implants may be selected to be alignable over their entire length. Alternatively, for example if an hour-glass shaped reducing implant is used, one flared section may be designed to be mis-aligned when the other flared section is aligned. Optionally, this embodiment is used to select if blood should flow into or out of the space between the implant and the blood wall, possibly affecting collapse of the vessel wall on the implant. The two reducing implants are, in some embodiments of the invention aligned inside the body. Alternatively or additionally, they are aligned outside the body. Optionally, the inner reducing implant is adapted to be mounted inside a reducing implant, rather than a vessel wall, for example, including short hard radial anchors, rather than a soft, smooth coating on its edge.

0038An aspect of some embodiments of the invention relates to a balloon adapted to be removed from a flow reducing implant with a narrowing, through the narrowing and after inflation. In an exemplary embodiment of the invention, the balloon or an outer sheath provided with the balloon comprises a plurality of somewhat flexible wires, which, when retracted through the narrowing and/or through an aperture defined in a delivery catheter, compress together, thereby radially compressing the balloon. Alternatively or additionally, the wires are not axially arranged, for example being spirally arranged, so that when the balloon deflates, the balloon will twist closed.

0039An aspect of some embodiments of the invention relates to a flow reducing graft-stent comprising a stent body, which may or may not define a narrowed portion and a graft section that is mounted on the stent, for example on its outside or with the stent embedded in the graft, wherein the graft does define a narrowing, for example the graft being generally cone shaped. The graft section is optionally held open using one or more stiffening elements and/or a ring at its narrowed section. Optionally, the graft is impervious to blood flow.

0040An aspect of some embodiments of the invention relates to a reducing implant mounted inside a support element, for example a stent, a graft or a stent graft. Optionally, this prevents damage of the surrounding vessel by the reducing implant. Alternatively or additionally, this allows the reducing implant to be more easily removed.

0041An aspect of some embodiments of the invention relates to reducing a vessel diameter using an external element, such as a band or clip. In an exemplary embodiment of the invention, a band is inserted outside the blood vessel and tightened, to reduce the diameter of a narrow and/or a wide section of the flow reducing implant. Such a band may be left in the body, or removed (e.g., be part of a tool), for example, if the flow reducing implant is plastically deformed by the tool. Alternatively or additionally, the band is used to force a collapsing of the vessel on the flow reducing implant, for example is such collapsing did not occur by itself.

0042An aspect of some embodiments of the invention relates to using a reducing implant in parts of the body other than the coronary veins and/or coronary sinus. In one example, a flow reducing implant is used to reduce flow through one or more veins in the leg resulting in redistribution of blood in the leg and/or triggering of angiogenesis or expansion of existing blood vessels. In another example, a flow reducing implant is used to reduce arterial blood flow to abnormal growths (e.g., tumors), such as growths in the uterus and/or growths in the Liver. A particular property of the liver and the uterus is that these organs receive blood from at least two different sources, while the growths in these organs often receive blood from only one of the sources. In addition, the normal tissue may be able to weather a sharp reduction in blood, while a tumor growth may not.

0043There is thus provided in accordance with an exemplary embodiment of the invention, a flow reducing implant, comprising:

0044a flared section adapted to contact a blood vessel wall;

0045at least one narrowed section continuous with said flared section; and

0046at least one anchor tab that lies generally in a plane of said flared section. Optionally, said implant is formed of a sheet material and wherein said tab is attached to a portion of said flared section that is generally parallel to a wall of said blood vessel, Alternatively or additionally, said anchor tab points axially. Alternatively or additionally, said anchor tab points towards said narrowed section. Alternatively or additionally, the implant comprises at least two opposing anchor tabs. Alternatively or additionally, the implant comprises at least two flared sections, each one with at least one anchor tab.

0047In an exemplary embodiment of the invention, said implant is plastically deformed to said configuration. Alternatively, said implant self-deforms to said configuration.

0048In an exemplary embodiment of the invention, said anchor tabs are blunt enough to generally prevent damage to said blood vessel.

0049There is also provided in accordance with an exemplary embodiment of the invention, a flow reducing implant, comprising:

0050a flared section adapted to contact a blood vessel wall;

0051at least one narrowed section continuous with said flared section and adapted to be narrowed after implantation. Optionally, the implant comprises an external ribbon adapted to selectively increasingly constrain said narrowing. Optionally, the implant comprises an impulser adapted to receive signals from outside the body and constrain said ribbon in response.

0052In an exemplary embodiment of the invention, said ribbon is expandable. Alternatively or additionally, said ribbon is inflatable.

0053In an exemplary embodiment of the invention, said ribbon is self-expands by absorption.

0054In an exemplary embodiment of the invention, said ribbon is tearable.

0055In an exemplary embodiment of the invention, said narrowed section comprises a plurality of engagement points adapted to be engaged, for radial constriction, by a catheter with matching engagers. Alternatively or additionally, said narrowed section is adapted to be selectively widened after implantation.

0056In an exemplary embodiment of the invention, said narrowed section is inflatable.

0057In an exemplary embodiment of the invention, said narrowed section is expandable in thickness.

0058There is also provided in accordance with an exemplary embodiment of the invention, a flow reducing implant, comprising:

0059a flared section adapted to contact a blood vessel wall;

0060at least one narrowed section continuous with said flared section; and

0061at least ribbon coupled to said narrowed section and adapted to define at least two discrete expansion states of said narrowed section. Optionally, said at least one ribbon comprises a tearable ribbon. Alternatively or additionally, said at least one ribbon comprises a ribbon with a sliding clasp and a plurality of stop positions defined thereon. Alternatively or additionally, said at least one ribbon comprises a plurality of ribbons, being different in at least one of initial diameter, tear strength and final diameter. Alternatively or additionally, said at least one ribbon comprises a sated ribbon having a first diameter and a second diameter set by said slits being closed or expanded. Alternatively or additionally, said at least one ribbon comprises a cord woven into said narrowed section.

0062In an exemplary embodiment of the invention, said at least one ribbon lies outside of said narrowed section.

0063In an exemplary embodiment of the invention, said at least one ribbon is biodegradable.

0064In an exemplary embodiment of the invention, said at least one ribbon blocks flow through a wall of said narrowed section.

0065There is also provided in accordance with an exemplary embodiment of the invention, a flow reducing implant, comprising:

0066a flared section adapted to contact a blood vessel wall;

0067at least one narrowed section continuous with said flared section,

0068wherein said implant comprises at least one overlapping section, whose overlap changes when said narrowed section is expanded. Optionally, said overlap comprises a plurality of overlapping cut-outs of said implant. Alternatively or additionally, said overlap comprises an overlap of substantially an entire length of said implant.

0069There is also provided in accordance with an exemplary embodiment of the invention, a flow reducing implant, comprising:

0070a stent-like element adapted to anchor in a tubular blood vessel; and

0071a flexible cone-shaped nozzle mounted on said stent, said cone shaped nozzle defining a narrowing that substantially reduces a cross-section of blood flow through said sent-like element. Optionally, said nozzle comprises at least one stiffener.

0072There is also provided in accordance with an exemplary embodiment of the invention, a flow reducing implant, comprising:

0073an open weave mesh that does not substantially impede blood flow, therethrough; and

0074a layer of graft material mounted on said mesh and defining a narrowed lumen for blood flow therethrough. Optionally, said open weave mesh forms an hourglass shape when expanded in said graft material layer.

0075There is also provided in accordance with an exemplary embodiment of the invention, a flow reducing implant, comprising:

0076a flared section adapted to contact a blood vessel wall;

0077at least one narrowed section continuous with said flared section,

0078wherein said implant is defined by a sheet material with slots and wherein a width of said slots varies over the implant to control an expanded geometry of said implant.

0079There is also provided in accordance with an exemplary embodiment of the invention, a flow reducing implant, comprising:

0080a flared section adapted to contact a blood vessel wall;

0081at least one narrowed section continuous with said flared section,

0082wherein said implant is defined by a sheet material with slots and wherein said slots are arranged in axial lines and wherein said alternating lines have different lengths of slots at a same axial position.

0083There is also provided in accordance with an exemplary embodiment of the invention, a flow reducing implant for reducing blood flow in a blood vessel, comprising:

0084a body having a cross sectional dimension; and

0085a restricting element that at least partially encircles a blood vessel. Optionally, said element pierces said blood vessel. Alternatively or additionally, said element comprises a tack or a suture. Alternatively or additionally, said element comprises a band. Optionally, said band comprises a ratchet mechanism that maintains it in position in respect to said vessel. Alternatively or additionally, said band comprises a plurality of expandable slits.

0086In an exemplary embodiment of the invention, said element comprises one of a clip, clasp and vise. Alternatively or additionally, said element comprises a spiral.

0087In an exemplary embodiment of the invention, said element comprises an expandable material. Optionally, said element is adapted to expand by expansion pressure from the interior of said blood vessel. Optionally, said implant is adapted to expand in response to expansion pressure of a balloon catheter.

0088There is also provided in accordance with an exemplary embodiment of the invention, a method of treating abnormal growth: in the body, comprising:

0089determining a source artery for the growth; and

0090inserting a flow reducing implant with an adjustable configuration into the determined artery, such that flow to the growth is reduced. Optionally, said growth is extant in an organ that is fed from multiple source arteries. Alternatively or additionally, said growth is fed by a single source artery. Alternatively or additionally, said growth comprises a leiomyoma. Alternatively or additionally, said growth comprises a malignant tumor. Optionally, said tumor is a liver tumor. Alternatively or additionally, said tumor is an encapsulated tumor.

0091There is also provided in accordance with an exemplary embodiment of the invention, a method of treating blood flow problems in a limb, comprising:

0092identifying at least one vein that if flow in the vein is reduced is expected to reduce the blood flow problem; and

0093inserting a flow reducing implant into the determined vein. Optionally, said vein is a deep vein. Alternatively, said vein is a surface vein.

0094There is also provided in accordance with an exemplary embodiment of the invention, a flow reducing implant comprising:

0095an outer generally tubular section adapted to be inserted in a blood vessel; and

0096an insert adapted to lodge in said tubular section, said insert designed to reduce blood flow passing through the blood vessel. Optionally, said generally tubular section is designed to reduce blood flow passing therethrough. Alternatively or additionally, said insert comprises a funnel shaped insert. Alternatively or additionally, said generally tubular section is designed to not reduce blood flow passing therethrough. Alternatively or additionally, said generally tubular section comprises a plurality of opening in its wall and wherein said insert comprises a plurality of opening in its wall. Optionally, said insert and said tubular section are rotationally alignable to modify an alignment of said pluralities of openings with each other.

0097There is also provided in accordance with an exemplary embodiment of the invention, a method of reducing flow in a blood vessel, comprising:

0098selecting a location in the vessel to narrow;

0099inserting a flow reducing implant into the blood vessel at the location; and

0100mounting a restricting element on said vessel at the location and over said flow reducing implant. Optionally, said restricting element reduces an inner diameter of said flow reducing implant. Optionally, said method comprises removing said restricting element.

BRIEF DESCRIPTION OF THE DRAWINGS

0101Non-limiting embodiments of the invention will be described with reference to the following description of exemplary embodiments, in conjunction with the figures. The figures are generally not shown to scale and any measurements are only meant to be exemplary and not necessarily limiting. In the figures, identical structures, elements or parts that appear in more than one figure are preferably labeled with a same or similar number in all the figures in which they appear, in which:

0102<figref idref="DRAWINGS">FIG. 1</figref> is a schematic showing of a flow reducing implant installed in a coronary sinus vein, in accordance with an exemplary embodiment of the invention;

0103<figref idref="DRAWINGS">FIG. 2</figref> is a schematic side view of a flow reducing implant, in accordance with an exemplary embodiment of the invention;

0104<figref idref="DRAWINGS">FIGS. 3A-3B</figref> are plan layouts of a slit-type flow reducing implant, in accordance with an exemplary embodiment of the invention;

0105<figref idref="DRAWINGS">FIG. 3C</figref> is an isometric vies of the flow reducing implant of <figref idref="DRAWINGS">FIG. 3A</figref> mounted on a balloon catheter delivery system, in accordance with an exemplary embodiment of the invention;

0106<figref idref="DRAWINGS">FIGS. 4A-4B</figref> are plan layouts of a slit-type flow reducing implant, in accordance with an exemplary embodiment of the invention;

0107<figref idref="DRAWINGS">FIGS. 4C-4D</figref> are a plan layout and isometric view, respectively, of a slit-type flow reducing implant with a smooth rim, in accordance with an exemplary embodiment of the invention;

0108<figref idref="DRAWINGS">FIG. 5</figref> is a vascular path to a coronary sinus, in accordance with an exemplary embodiment of the invention;

0109<figref idref="DRAWINGS">FIGS. 6A-6C</figref> are three exemplary vise embodiments that reduce flow through a blood vessel, in accordance with an exemplary embodiment of the invention;

0110<figref idref="DRAWINGS">FIGS. 6D-6F</figref> show three exemplary clamp embodiments that reduce blood flow through vessel <b>1002</b>, in accordance with exemplary embodiments of the invention

0111<figref idref="DRAWINGS">FIG. 6G</figref> illustrates an exemplary endoscopic tool for releasing a blood vessel reducing clip, in accordance with an exemplary embodiment of the invention;

0112<figref idref="DRAWINGS">FIGS. 7A and 7B</figref> are a plan view and an isometric view of a flow reducing implant embodiment with anchors, in accordance with an exemplary embodiment of the invention;

0113<figref idref="DRAWINGS">FIG. 8A</figref> is a portion of a plan layout of a section of a flow reducing implant with selective narrowing control, in accordance with an exemplary embodiment of the invention;

0114<figref idref="DRAWINGS">FIG. 8B</figref> is a side cross-sectional view of a flow reducing implant and a matching catheter for reducing a diameter of the flow reducing implant, in accordance with an exemplary embodiment of the invention;

0115<figref idref="DRAWINGS">FIG. 8C</figref> is a two-part flow reducing implant, in accordance with an exemplary embodiment of the invention;

0116<figref idref="DRAWINGS">FIG. 8D</figref> is a flow reducing implant and insert, in accordance with an exemplary embodiment of the invention;

0117<figref idref="DRAWINGS">FIG. 8E</figref> is an isometric view of a dual layer flow reducing implant, in accordance with an exemplary embodiment of the invention;

0118<figref idref="DRAWINGS">FIGS. 9A-9G</figref> are embodiments of flow reducing implant, in accordance with exemplary embodiments of the invention;

0119<figref idref="DRAWINGS">FIGS. 10A-10B</figref> are an isometric view and detail, respectively, of a ringed mesh-type flow reducing implant embodiment, in accordance with an exemplary embodiment of the invention;

0120<figref idref="DRAWINGS">FIG. 11</figref> is an isometric view of a partially covered mesh-type flow reducing implant embodiment, in accordance with an exemplary embodiment of the invention.

0121<figref idref="DRAWINGS">FIG. 12</figref> is an isometric view of a sheath-type flow reducing implant, in accordance with an exemplary embodiment of the invention;

0122<figref idref="DRAWINGS">FIG. 13</figref> is longitudinal section of an inflatable tube-type flow reducing implant, in accordance with an exemplary embodiment of the invention;

0123<figref idref="DRAWINGS">FIG. 14</figref> is a longitudinal section of a flow reducing implant with shape-conforming elements, in accordance with an exemplary embodiment of the invention; and

0124<figref idref="DRAWINGS">FIG. 15</figref> is a plan layout of a cord-type flow reducing implant, in accordance with an exemplary embodiment of the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

0125<figref idref="DRAWINGS">FIG. 1</figref> is a schematic showing of a flow reducing implant <b>100</b> installed in a coronary sinus vein <b>102</b>, in accordance with an exemplary embodiment of the invention. Coronary sinus <b>102</b> drains a plurality of cardiac veins <b>106</b> into a right atrium <b>104</b>. The cardiac circulation is generally hierarchical and comprises of stages of reducing (or increasing) diameter. Thus, veins <b>106</b>, in turn, drain a plurality of thin venules <b>108</b>, which, after a few stages, drain a plurality of capillaries <b>110</b>. Capillary <b>110</b> is fed by a plurality of arterioles <b>112</b>, which, after a few stages, are fed by a plurality of coronary arteries <b>114</b> and <b>120</b>. A stenosis <b>116</b> is shown in a coronary artery <b>114</b>. While the cardiac circulation is generally hierarchical, some connection exists between different branches. Occasionally, the existence of stenosis <b>116</b> will cause a collateral connection <b>118</b> to spontaneously form (or widen an existing connection) between coronaries <b>114</b> and <b>120</b>, bypassing stenosis <b>116</b>.

0126In some cases, however, this spontaneous formation does not occur. In an exemplary embodiment of the invention, a flow reducing implant <b>100</b> is placed in coronary sinus <b>102</b> and has a narrowing significant enough to encourage the formation of collateral connection <b>118</b>. It is hypothesized that collateral connection <b>118</b> is caused by an increase in venous blood pressure, which, in turn, increases the pressure in the capillaries and/or causes retro-flow in the capillaries and/or causes drainage of the capillaries directly into the heart. However, even if this hypothesis is incorrect, several studies, that included numerous experiments and actual procedures have shown that constriction of coronary sinus <b>102</b> will generally cause the formation of collateral circulation and/or otherwise improve the condition of patients with blocked coronary arteries. Alternative or additional hypotheses that are optionally used to select the constrictive effect of flow reducing implant <b>100</b> include:

0127(a) Flow reducing implant <b>100</b> increases the pressure in the coronary capillaries, thus increasing perfusion duration.

0128(b) An increase in resistance of the venous system causes redistribution of blood flow in coronary arteries.

0129(c) An increase in resistance of venous system increases intra-myocardial perfusion pressure and/or intra-myocardial pressure.

0130(d) Increasing the arterial diastolic pressure (by restricting venous drainage) causes the arterial auto-regulation to start working again, for example, such an auto regulation as described in Braunwald “Heart Disease: A Textbook of Cardiovascular Medicine”, 5th Edition, 1997, W.B. Saunders Company, Chapter 36, pages 1168-1169.

0131It should be noted that the selection of flow reducing implant <b>100</b> may be made to achieve one or more of the above suggested effects, optionally to a desired degree and/or taking into account safety issues, such as allowing some drainage and maximum pressure allowed by the coronary venous drainage system.

0132<figref idref="DRAWINGS">FIG. 2</figref> is a schematic side view of flow reducing implant <b>100</b>, in accordance with an exemplary embodiment of the invention. Flow reducing implant <b>100</b> comprises a narrowed section <b>204</b> and at least one flared section <b>200</b> (and <b>202</b>) leading into narrowed section <b>204</b>. Section <b>200</b> (and <b>202</b>) includes sections <b>210</b> and <b>206</b> that are inclined relative to the wall of coronary sinus <b>102</b> and sections <b>212</b> and <b>208</b> that are parallel to the wall.

0133In the exemplary embodiment and measurements shown, flow reducing implant <b>100</b> is expandable and shortens somewhat during expansion: having a length of 20 mm before expansion and about 18.8 mm after expansion. Optionally, a non-shortening design is used, for example a mesh as in peristaltic stents, such as described in U.S. Pat. No. 5,662,713, the disclosure of which is incorporated herein by reference. An exemplary material thickness is 0.15 mm, however, thinner or thicker materials may be used. Other exemplary lengths are 5 mm, 12 mm, 24 mm, 35 mm 45 mm and any smaller, intermediate or larger size. The length is optionally selected to match a physiological size of the target vein (e.g., length and curves) and/or to ensure good contact with vein walls. The length of narrowed section <b>204</b> may be, for example, 0.5 mm, 1 mm, 2 min, 3 mm, 5 mm or any smaller, intermediate or larger length, for example selected to achieve desired flow dynamics An exemplary inner diameter of the flared sections is between 2 mm and 30 mm, for example, 5 mm, 10 mm, 15 mm, 20 mm or any larger, smaller or intermediate diameter, for example selected to match the vein diameter. The inner diameter of the narrowed section may be, for example, 1 mm, 2 mm, 3 mm, 5 mm, 10 mm or any smaller, larger or intermediate diameter, for example selected to achieve desired flow dynamics and/or a pressure differential across the flow reducing implant.

0134In an exemplary embodiment of the invention, the ratio between the cross-section of narrowed section <b>204</b> and the flares of flow reducing implant <b>100</b> is 0.9, 0.8, 0.6, 0.4, 0.2 or any larger, smaller or intermediate ratio, for example selected to achieve desired flow dynamics and/or a pressure differential across the flow reducing implant.

0135While a circular cross-section is shown, other cross-sections may be used, for example, polygonal and ellipsoid. A potential advantage of non-circular cross-sections is that the implant is less likely to migrate axially and/or rotate. Alternatively or additionally, the outside of the flow reducing implant is roughened and/or otherwise adapted to adhere to the vein wall. The cross-section shape and/or orientation optionally changes along the length of flow reducing implant <b>100</b>.

0136<figref idref="DRAWINGS">FIG. 3A</figref> is a plan layout of a slit-type flow reducing implant and <figref idref="DRAWINGS">FIG. 3B</figref> is a detail of <figref idref="DRAWINGS">FIG. 3A</figref>, in accordance with an exemplary embodiment of the invention. In this plan layout, the ends of sections <b>200</b> and <b>202</b> are caused to be parallel to the vessel wall when flow reducing implant <b>100</b> is expanded.

0137In an exemplary embodiment of the invention, the outside flare of flow reducing implant <b>100</b> is defined by sections <b>340</b>, <b>342</b> and <b>344</b>, shown in <figref idref="DRAWINGS">FIG. 3B</figref>. Optionally, the total length of these sections defines the maximum flare length. Alternatively or additionally, the bending areas in and between these sections define the relative force required to expand the flare region relative to the area near the rim. If the rim region is more difficult to expand and/or is expanded less than the adjacent regions, the expansion of flow reducing implant <b>100</b> will tend to cause the rim to be bent in, or at least not flare out. Alternatively, in a self-expanding flow reducing implant, the existence of sections <b>340</b>, <b>342</b> and <b>344</b> can be used to determine the final shape of the flare. Optionally, additional sections <b>346</b> are provided around the circumference of flow reducing implant <b>100</b>, which define outer slits in flow reducing implant <b>100</b>, which outer slits may have a maximum expansion that is the same or smaller than that nearby (axially inwards) slits. This design can also be used to control the shape of the flare.

0138In an exemplary embodiment of the invention, a flow reducing implant is characterized by this maximum diameter, which may be used, for example, for selecting a particular flow reducing implant to match a patient. Optionally, during expansion, the balloon is aligned with flow reducing implant <b>100</b> so that it only contacts the flare region or only contacts the non-flare regions of flow reducing implant <b>100</b>.

0139<figref idref="DRAWINGS">FIG. 3C</figref> is an isometric view of flow reducing implant <b>100</b> (<figref idref="DRAWINGS">FIG. 3A</figref>), mounted on a balloon catheter delivery system <b>302</b>, in accordance with an exemplary embodiment of the invention.

0140In an exemplary embodiment of the invention, flow reducing implant <b>100</b> is formed by cutting out of a sheet of metal or a tube, for example, using laser, water cutting, chemical erosion or metal stamping (e.g., with the result being welded to form a tube). Alternatively, flow reducing implant <b>100</b> is woven (e.g. of metal or plastic fiber), for example, using methods as well known in the art. Optionally, narrowed section <b>204</b> is made using a different method from flared sections <b>200</b> and <b>202</b>, for example, the flared sections being woven and the narrowed section being cut from sheet metal. In an alternative embodiment of the invention, flow reducing implant <b>100</b> includes with a constraining ring that prevents the expansion of narrowed section <b>204</b>. Optionally, the restraining ring is plastically expandable, possibly under a higher pressure than the rest of flow reducing implant <b>100</b>, which may be plastically deformable or self-expanding. Alternatively or additionally, the restraining ring is selected to set the desired degree of narrowing, and then mounted on a flow reducing implant, a stent or a stent graft, for implantation. In a sleeve flow reducing implant (<figref idref="DRAWINGS">FIG. 9G</figref>) a similar effect may be achieved by suturing the stent graft.

0141Upon attaining its destination, a standard balloon catheter with a single expansion area, for example the Fox Catheter™ by Jomed, inc., may be used to encourage the implant to attain its contoured shape. As the balloon presses against lumen of the implant, the narrowed section is prevented from expanding while flared sections <b>200</b> and <b>202</b> expand under pressure. Various methods for preventing the narrow section from expanding are described below, for example, providing different mechanical properties, different designs or additional elements at the narrowed sections relative to the non-narrowed sections.

0142In an alternative embodiment, flow reducing implant <b>100</b> is cut out of a sheet and then spirally twisted around a mandrel to form the shape of flow reducing implant <b>100</b>. Alternatively, flow reducing implant <b>100</b> is cut out of a tube, with the flared parts being spiral cuts and the narrowing part being a ring cut. Alternatively, flow reducing implant <b>100</b> is formed as a coil spring, with axially varying relaxation positions.

0143In an exemplary embodiment of the invention, flow reducing implant <b>100</b> is adapted for use in a coronary sinus or other coronary vein or other veins having non-muscular walls. Veins are typified by having a low degree of elasticity and being relatively sensitive to tears (as compared to arteries). In one example, the edges of flow reducing implant <b>100</b> are curved inwards or curled, for example as shown by reference <b>130</b> in <figref idref="DRAWINGS">FIG. 1</figref>, Alternatively or additionally, the edges are folded back and/or smoothed to remove sharp edges. Alternatively, the parallel sections <b>208</b> and <b>212</b> (<figref idref="DRAWINGS">FIG. 2</figref>) are made long enough to support flow reducing implant <b>100</b> without harming coronary sinus <b>102</b>. Alternatively or additionally, flow reducing implant <b>100</b> or at least a larger diameter portion thereof, is made soft enough and/or with a low spring constant, to prevent flow reducing implant <b>100</b> from applying too much pressure on the coronary flow reducing implant wall. Alternatively or additionally, the flares of flow reducing implant <b>100</b> are coated with a biologically inert flexible coating, for example, a soft silicone elastomer or another soft plastic or rubber material such as Latex, Teflon and/or Polyurethane (for example Angioflex, a biologically inert polyurethane plastic).

0144<figref idref="DRAWINGS">FIGS. 4A-4B</figref> are plan layouts of slit-type flow reducing implant <b>100</b>, in accordance with an exemplary embodiment of the invention. In <figref idref="DRAWINGS">FIG. 4B</figref>, rim <b>402</b> is defined by sections <b>440</b> and <b>446</b>. As shown, these sections are designed to provide a relative smooth rim, possibly with small amounts of distortion (so rim <b>402</b> remains smooth) where the sections connect to sections <b>442</b> and <b>444</b>. Together, sections <b>442</b>, <b>444</b> and <b>446</b> define outer slits for rim <b>402</b>.

0145Patients that are candidates for an angiogenesis-promoting procedure may have significant vascular compromise of the coronary circulation with constriction and/or lack of flow in one or more coronary arteries that supply blood to the coronary tissue. An invasive surgical procedure, even to percutaneously introduce and/or position a reducing implant <b>100</b> into the coronary sinus, may trigger a cardiovascular accident with untoward sequella. Hence, averting and/or limiting the amount of time that the vasculature is invaded, for example, during use of a balloon catheter is desirable in some individuals.

0146<figref idref="DRAWINGS">FIGS. 4C-4D</figref> are a plan layout and isometric view, respectively of a slit-type flow reducing implant <b>1100</b> with a smooth rim, in accordance with an exemplary embodiments of the invention.

0147In an exemplary embodiment of the present invention, slit-type flow-reducing implant <b>1100</b> comprises shape memory materials that automatically achieve a final configuration state upon exiting, for example, a delivery catheter or sheath, thereby averting the use of a balloon catheter for initial installation of slit-type flow-reducing implant <b>1100</b>. Alternatively, a balloon expended material, for example one that plastically deforms by expansion, may be used.

0148In an exemplary embodiment, slit-type coronary flow-reducing implant <b>1100</b>, shown in a plan view in <figref idref="DRAWINGS">FIG. 4C</figref>, contains preformed slits <b>1102</b>, in accordance with an exemplary embodiment of the invention. Slits <b>1102</b> (and optionally a set of slits <b>1104</b> in a second or further row) define a row <b>1122</b> (and a row <b>1124</b>) along an outer edge <b>1132</b> of slit-type flow-reducing implant <b>1100</b> that, in the unexpanded state comprise at least one edge <b>1132</b> that has a wavy configuration. Upon expansion, for example shown in <figref idref="DRAWINGS">FIG. 4D</figref>, edge <b>1132</b> becomes smooth while slits <b>1102</b> assume a rectangular appearance, with edge <b>1132</b> transverse to a slit <b>1126</b>, for example. In an exemplary embodiment of the invention, the slits of the rim are wider than the slits of the rest of implant <b>1100</b>, thereby affecting its final expanded configuration.

0149In an exemplary embodiment of the present invention, slit-type coronary flow-reducing implant <b>1100</b> is transferred to its deployment site in coronary sinus using a guide sheath without accompaniment by a balloon catheter. As slit-type coronary flow-reducing implant <b>1100</b> reaches its destination and exits its guide sheath, coronary flow-reducing implant <b>1100</b> automatically expands into its final shape, shown in <figref idref="DRAWINGS">FIG. 4D</figref>. In this manner, slit-type coronary flow-reducing implant <b>1100</b> does not require manipulation and/or expansion using, for example, a balloon catheter.

0150Alternatively or additionally, a balloon catheter may be used to facilitate expansion of slit-type flow-reducing implant <b>1100</b>, for example, when it is made of materials that do not automatically attain a memorized shape. In an exemplary embodiment, rows of slits <b>1122</b> and/or <b>1124</b> have lengths and/or orientations that promote flow-reducing implant <b>1100</b> to form into a final shape under pressure of a balloon catheter, therefore, installing with a minimal amount of time and/or stress to the surrounding tissue.

0151In an exemplary embodiment, slit-type coronary flow-reducing implant <b>1100</b> is designed to alter its shape in response to manipulation and/or expansion following installation. In an exemplary embodiment, slits <b>1138</b> expand so that a narrow passage <b>1168</b> automatically attains a first diameter during installation. In an exemplary embodiment, following installation of slit-type coronary flow-reducing implant <b>1100</b>, a balloon catheter is introduced into narrow passage <b>1168</b> and inflated to press radially outward on narrow passage <b>1168</b>. In an exemplary embodiment, a pressure, for example, of between 7 and 8 atmospheres or less than 7 or greater than 8 atmospheres, depending, for example on the stiffness of the component materials, causes expansion slits <b>1138</b> to expand to a larger cross section. This causes narrow section <b>1168</b> to have a larger diameter than it had immediately following installation.

0152While not shown, some of the slits, for example slits <b>1138</b> may be oblique, thus possibly requiring a different degree of force to expand and/or providing a twisting of the deployed implant. Providing opposing oblique slits may be used to providing a shortening of the implant.

0153In an exemplary embodiment, when flow-reducing implant <b>1100</b> is installed, little or no blood migrates through the walls of narrow passage <b>1168</b> and/or a flare <b>1160</b> to contact the walls of the coronary sinus. This, for example, is achieved by a narrow configuration of the slits. Alternatively or additionally, the length of the slits decreases near narrowing <b>1168</b>.

0154In an exemplary embodiment, to achieve limitation and/or cessation of blood flow through the implant walls, the slits (e.g., not only slits <b>1102</b> and <b>1104</b> at the rim) are increased in number, while their width is reduced. The viscosity of the blood impedes its flow through the decreased width of the slits while the increased number of slits may fosters expansion of implant <b>1100</b>. This may result in a net reduction in blood flow through the implant walls.

0155Alternatively or additionally, the slit width may be used to help define the device geometry. For example, slits (actually spaces) <b>1104</b> are wider than the other slits. If, for example, slits <b>1104</b> are made wider than slits <b>1102</b>, a curved in rim may result.

0156Also shown is an optional design in which slits are arranged in alternating rows of long and short slits. Alternatively or additionally and as shown, the size and/or density of slits is larger near the rims than near the center of implant <b>1100</b>. Alternatively or additionally and as shown, the length of the slits increases as a function of the distance from narrowing <b>1168</b>.

0157As shown in <figref idref="DRAWINGS">FIG. 4D</figref>, the material of implant <b>1168</b> is distorted by the expansion. Alternatively or additionally, the slits are distorted and the material is distorted to conform to these distortions. For example, in one implantation, the short axial slit nearest the rim achieves a trapezoid rather than rectangular shape. In general, the expanded configurations are idealized, with an actual expanded shape possibly including step-like distortions caused by the discrete pattern of the slits in the implant.

0158<figref idref="DRAWINGS">FIG. 5</figref> shows a vascular path to coronary sinus <b>102</b>, in accordance with an exemplary embodiment of the invention. Desirably, flow reducing implant <b>100</b> is implanted using a trans-vascular approach, for example, from the venous system or by crossing through an intra-chamber wall in the heart. In an exemplary embodiment of the invention, the delivery system is inserted through a jugular vein <b>510</b> or a subclavian vein <b>512</b> to a right atrium <b>506</b> of a heart <b>500</b> via a superior vena cava <b>508</b> and/or a femoral vein <b>502</b>, via an inferior vena cava <b>504</b>. Once in right atrium <b>506</b>, the delivery system is guided (e.g., through a sharp bend) to an opening <b>514</b> into coronary sinus <b>102</b>. In some patients, a valve exists at the entrance to coronary sinus <b>102</b>.

0159<figref idref="DRAWINGS">FIGS. 6A-6C</figref> are three exemplary vise embodiments, <b>1000</b>, <b>1010</b> and <b>1020</b>, that reduce flow through a blood vessel <b>1002</b>, and are applied from outside the blood vessel, in accordance with exemplary embodiments of the invention. Vise <b>1000</b> (<figref idref="DRAWINGS">FIG. 6A</figref>) is a band having any ratchet mechanism for preventing opening as known in the art; vise <b>1010</b> is a clip-like clasp; and vise <b>1020</b> is an elastic spiral.

0160In an exemplary embodiment of the invention, the band, clip and/or spiral are distortable. In one example, if the narrowing is too great, a balloon catheter can be inserted into the vessel and expanded, causing the spiral, clip and/or band to distort. In one example, the band comprises a plurality of slits (e.g., as in <figref idref="DRAWINGS">FIG. 8A</figref>), that accommodate such distortion.

0161<figref idref="DRAWINGS">FIGS. 6D-6F</figref> show three exemplary clamp embodiments, <b>1030</b>, <b>1040</b> and <b>1050</b>, that reduce blood flow through vessel <b>1002</b>, in accordance with exemplary embodiments of the invention. Clamp <b>1030</b> is a clip that shuts down part of the cross-section of vessel <b>1002</b>; clamp <b>1040</b> is also a clip, that only distorts the cross-section of vessel <b>1002</b>; and clamp <b>1050</b> is a tack (or suture) that transfixes a part of vessel <b>1002</b>. Non-piercing clips are optionally designed to have rounded tip and/or non-meeting tips to reduce danger of piercing.

0162<figref idref="DRAWINGS">FIG. 6G</figref> illustrates an exemplary endoscopic tool <b>1060</b> for releasing blood vessel reducing clip <b>1010</b>, in accordance with an exemplary embodiment of the invention. Clip <b>1010</b> is held between a flat plate <b>1060</b> and a Trans-axially movable arm <b>1062</b> with a broadened tip. Retracting arm <b>1062</b> towards tool <b>1060</b> causes the clip to open and moving arm <b>1062</b> in a Trans-axial direction frees the clip. Various other clip deployment mechanisms (for plastic and elastic materials) are known in the art and may be used. In an exemplary embodiment of the invention, the procedure is performed through a key hole and using a working channel or a different keyhole to provide visual verification of the procedure. Alternatively or additionally, radiological verification may be provided. Various implants are known in the art for applying bands to blood vessel and may be used for the example of <figref idref="DRAWINGS">FIG. 6A</figref> as well.

0163Flow-reducing implants <b>1000</b>, <b>1010</b>, <b>1020</b>, <b>1030</b>, <b>1040</b> and/or <b>1050</b> may be deployed on vessel <b>1002</b>. Alternatively, these implants may be deployed onto tissue enclosing vessel <b>1002</b>. For example, in the case of the coronary sinus, the implant may be deployed onto (and/or piercing through) a pericardium and/or cardiac muscle tissue.

0164<figref idref="DRAWINGS">FIGS. 7A and 7B</figref> are a plan view and an isometric view of a flow reducing implant <b>1200</b> with anchors, in accordance with an exemplary embodiment of the invention.

0165In an exemplary embodiment of the present invention, an anchor-type flow-reducing implant <b>1200</b> comprises at least one anchor <b>1202</b> that prevents motion of anchor-type flow-reducing implant <b>1200</b> in relation to a blood vessel. Optionally, at least one anchor <b>1202</b> and/or <b>1204</b> are parallel to the blood vessel and catch on the tissue of the blood vessel to prevent displacement of anchor-type implant <b>1200</b>. While the anchors are shown as flat, blunt and axial tabs, other designs may be used, for example, sharp, curled and/or oblique to the vessel axis.

0166Alternatively or additionally, implant <b>1200</b> comprises one of row of anchors <b>1202</b> and/or row of anchors <b>1204</b> that prevent motion. In an exemplary embodiment, anchors <b>1202</b> and/or <b>1204</b> are substantially parallel to the longitudinal axis of implant <b>1200</b> when it is in the non-expanded state and in the expanded state, shown in <figref idref="DRAWINGS">FIG. 7B</figref>. In an exemplary embodiment of the invention, this parallel layout is achieved by the anchors being attached only to the rims and not the flaring section of the implant. thus, they tend to stay in the plane of the rim, which may be, for example parallel to the blood vessel wall or even pointing the anchors towards the wall (e.g., if the rim is curled in)

0167In an exemplary embodiment, anchor <b>1202</b> and/or <b>1204</b> are connected to anchor-type flow-reducing implant <b>1200</b> and protrude from its surface to into the surrounding tissue with a pressure sufficient to prevent motion of the implant without causing tissue irritation. This can be important in veins, for example, that have less thickness than comparable arteries.

0168In an environment where the vascular tissue is not uniform in diameter and/or tends to stretch, for example in the coronary sinus, or in other situations, anchors that press with greater force or are pre-stressed to a greater non-parallel angle into the surrounding tissue may be desirable. In an exemplary embodiment, anchor <b>1202</b> and/or <b>1204</b> are designed for such a vessel and press radially outward from the wall of anchor-type flow-reducing implant <b>1200</b>, against the surrounding tissue.

0169The design of anchor-type flow-reducing implant <b>1200</b> includes anchors <b>1202</b> that have a free end that is not attached to narrow passage <b>1168</b> and, for example, blunt to avert tissue irritation. In an exemplary embodiment, one or more deployed anchors <b>1202</b> are parallel to a longitudinal axis <b>1210</b> of anchor-type flow-reducing implant <b>1200</b>, and point towards one or more anchors <b>1204</b>.

0170At a merging point of two vessels, the vessels may form a lumen with an ellipsoid cross section. An anchor-type flow-reducing implant with anchors <b>1202</b> and/or <b>1204</b> that point toward one another may tend to migrate laterally and/or displace to one side of the other of the lumen. In an exemplary embodiment, anchors <b>1202</b> and/or <b>1204</b> of anchor-type flow-reducing implant <b>1200</b> may be configured to compensate for not-cylindrical implantation environments.

0171For example, anchors <b>1202</b> and/or <b>1204</b> may be configured to point in a substantially perpendicular direction to longitudinal axis <b>1210</b> of anchor-type flow-reducing implant <b>1200</b>, thus tending to prevent lateral movement of implant <b>1200</b>. In still another embodiment, anchors <b>1202</b> and/or <b>1204</b> may be connected to an edge <b>1232</b> and pointing away from anchors <b>1204</b> that are connected to an edge <b>1234</b>. In this way, anchors <b>1202</b> and/or <b>1204</b> press into tissue at the edge of the implant that is stronger and/or exhibits a more uniform circumference.

0172Alternatively or additionally, anchors <b>1202</b> and/or <b>1204</b> can be oriented in an oblique direction oblique to a transverse axis <b>1220</b> and/or longitudinal axis <b>1210</b>, for example, to prevent migration in an environment where there is strong flow force of the blood stream that tends to exert force and displace implant <b>1200</b>.

0173While the anchors are shown cut out of the long slits, alternatively or additionally, the anchors may be cut out of short slits, for example a slit <b>1125</b>.

0174<figref idref="DRAWINGS">FIG. 8A</figref> is a portion of a plan layout of a section of a flow reducing implant <b>800</b> with selective narrowing control, in accordance with an exemplary embodiment of the invention. Flow-reducing implant <b>800</b> includes a narrowed section <b>804</b>. However, section <b>804</b> is also expandable, for example, having a plurality of thin slits <b>806</b> defined therein. This allows the minimum diameter of flow-reducing implant <b>800</b> to be increased after deployment.

0175In an exemplary embodiment of the invention, section <b>804</b> is stiffer than the rest of flow-reducing implant <b>800</b>, so that pressure suitable for expanding flow-reducing implant <b>800</b> will not expand section <b>804</b>. Alternatively, flow-reducing implant <b>800</b> is a self-deploying implant and section <b>804</b> is plastically deformed using a balloon. Thus, a delivery system used for flow-reducing implant <b>800</b> may include both a restraining element and a balloon element. In case the implantation of a flow-reducing implant fails, extreme expansion of section <b>804</b> will substantially negate the function of flow-reducing implant <b>800</b> and may allow a new flow-reducing implant to be implanted within or through flow-reducing implant <b>800</b>, at a later time.

0176Alternatively, as shown, two sizes of slits <b>806</b> are provided, with the degree of resistance to defamation being determined by the sizes and/or relative sizes of the slits.

0177<figref idref="DRAWINGS">FIG. 8B</figref> is a side cross-sectional view of a flow reducing implant <b>820</b> and a matching reducing catheter <b>840</b>, which can be used to reduce the narrowing of implant <b>820</b>, in accordance with an exemplary embodiment of the invention. Flow-reducing implant <b>820</b> can be formed generally like flow-reducing implant <b>800</b>, in that its narrowed section has a selectable diameter. Flow-reducing implant <b>820</b> includes a plurality of engagement points <b>822</b> that are adapted to be engaged by a plurality of engagers <b>846</b> of a catheter <b>840</b>. Various designs of engagers and engagement points may be used. In the example shown, engagement points <b>822</b> include a protruding arc <b>824</b> that is engaged by a barbed tip at engager <b>846</b>. In an exemplary embodiment of the invention, catheter <b>840</b> includes a body having a diameter similar to (or smaller, e.g., to allow for spring-back) the desired final diameter of flow-reducing implant <b>840</b>. When engagers <b>846</b> are inserted adjacent to engagement points <b>822</b> and catheter <b>840</b> is rotated, the barbs engage the arcs. One or more wires <b>844</b> are retracted, retracting engagers <b>846</b> and arcs <b>824</b> towards catheter body <b>842</b>. In an exemplary embodiment of the invention, body <b>842</b> distorts barbs <b>846</b> so that they release arcs <b>824</b> so that catheter <b>840</b> can be removed. Alternatively, other engagement/release mechanisms can be used, for example, barbs that match apertures in flow-reducing implant <b>820</b> or provision of grasping heads (e.g., pliers) at engagers <b>846</b>. Optionally, the narrowing procedure is performed under medical imaging, for example, fluoroscopy.

0178In an alternative embodiment of the invention, engagement means such as barbs <b>846</b> are used to remove the entire flow-reducing implant, optionally for replacement with a different flow-reducing implant and/or re-deployment of the same flow-reducing implant using a balloon on catheter <b>840</b> or after removal from the body.

0179Alternatively or additionally, the flow-reducing implant is removed in the following manner. Flow-reducing implant <b>820</b> is a shape memory flow-reducing implant that expands when subjected to body temperature. A balloon having cool fluid circulating there through is brought into flow-reducing implant <b>820</b> to cause flow-reducing implant <b>820</b> to shrink back to an unexpanded configuration and/or be more amenable for removal.

0180In some cases however, the decision to remove and/or change a diameter may be made only after a time period, during which vascular tissue may have grown into and attached onto flow-reducing implant <b>820</b>.

0181<figref idref="DRAWINGS">FIG. 8C</figref> is a two-part flow reducing implant <b>850</b> including a tubular section <b>852</b> and a reducing section <b>854</b>, in accordance with an exemplary embodiment of the invention, Reducing section <b>854</b> may be manufactured to match tubular section <b>852</b> or it may be a flow-reducing implant design as described herein or a flare, for example. In either case, tubular section <b>852</b> is optionally used to isolate reducing section <b>854</b> from the enclosing vascular tissue, thus allowing easier manipulation and/or replacement of section <b>854</b>. Alternatively or additionally, for example in the coronary sinus, the use of tubular section <b>852</b> may be desirable for prevention of damage to the vascular tissue. Alternatively or additionally, tubular section <b>852</b> is provided for other reasons, for example, to provide support for axial fixation of reducing section <b>854</b> and/or to reduce damage to a surrounding blood vessel. Depending on the embodiment, tubular section <b>852</b> and reducing section <b>854</b> may be of similar sizes or tubular section <b>852</b> may be considerably longer, for example, 25%, 50%, 100%, 200%, 400% or any smaller, intermediate or greater size ratio. The two sections may be inserted at the same time or at different procedures. The two sections may be inserted using a same delivery system or, for example, using two separate delivery systems. Tubular section <b>852</b> may be of various designs, for example, be a coil or mesh stent, a stent graft, a graft with stents (or other attachment means) at its ends and/or a plain graft. Tubular section <b>852</b> and/or the tips of a flow-reducing implant may be made flexible and/or elastic to adapt to changes in blood vessel diameter.

0182<figref idref="DRAWINGS">FIG. 8D</figref> is a flow reducing implant <b>860</b> including a narrowing insert to reduce the diameter of implant <b>860</b>, in accordance with an exemplary embodiment of the invention. Insert <b>870</b> has its expansion inside flow-reducing implant <b>860</b> limited by a narrowed diameter section <b>862</b> of flow-reducing implant <b>860</b>. In an exemplary embodiment of the invention, insert <b>870</b> has a funnel shape, with a narrow diameter opening <b>874</b> and a larger diameter opening <b>876</b>. Insert <b>870</b> may be formed, for example, from a mesh and may be plastically, elastically, super-elastically and/or shape-memory deformed. In an exemplary embodiment of the invention, the final geometry of insert <b>870</b> is defined by its resting points against flow-reducing implant <b>860</b>. This resting points comprise, for example, a point <b>864</b> generally between the narrow and flared sections of flow-reducing implant <b>860</b> and a resting point <b>866</b> on the flared section of flow-reducing implant <b>860</b>. In an exemplary embodiment of the invention, a ratchet mechanism is provided to anchor insert <b>870</b> in place. Optionally, opening <b>874</b> is narrowed further (if required), by advancing opening <b>876</b> towards narrowed section <b>862</b> of flow-reducing implant <b>860</b>. Alternatively or additionally, overcoming the ratchet mechanism and retracting opening <b>876</b> from section <b>862</b> enlarges opening <b>874</b>. In an exemplary embodiment of the invention, the ratchet mechanism comprises a plurality of inclined barbs or anchors <b>868</b>, on flow-reducing implant <b>860</b>. Alternatively or additionally, the ratchet mechanism and/or locking mechanism comprises a barb <b>872</b> on insert <b>870</b>. These ratchets may be overcome, for example, by reducing the size of opening <b>876</b> and/or by applying considerable force against the ratchet direction.

0183Alternatively or additionally to the above described methods of narrowing an implanted flow-reducing implant, in an exemplary embodiment of the invention, a band or clip is applied to the outside of the enclosing blood vessel, urging flow-reducing implant <b>820</b> (e.g., at its narrow and/or broad sections) to close. Alternatively, the band is applied alone, without a flow-reducing implant. Exemplary bands and other implants are described in <figref idref="DRAWINGS">FIG. 6A-6G</figref>. Such implants may be used to plastically urge flow-reducing implant <b>820</b> closed, in which case, a pliers (optionally adapted to pass through a keyhole) may be used instead of a permanent clamp. The jaws of the pliers are optionally formed to have a cross-section matching desired cross-section of flow-reducing implant <b>820</b>.

0184Alternatively, flow-reducing implant <b>820</b> is elastic or super-elastic, and a permanent implant is implanted outside the blood vessel. In an exemplary embodiment of the invention, the band or pliers is applied over a wide area, for example, 30%, 50%, 80% or any greater intermediate or smaller percentage of the length of flow-reducing implant <b>820</b>, to reduce damage to the blood vessel. Alternatively or additionally, the narrowing effect is applied to a weakened part of flow-reducing implant <b>820</b>, for example, a broad section thereof.

0185In some locations, for example in larger arteries exhibiting large flow volume and/or blood pressure, flow of blood through slits <b>1125</b> (<figref idref="DRAWINGS">FIG. 7B</figref>) may add to turbulence of blood flowing through flow-reducing implant <b>1100</b>. Such turbulence may contribute to the formation of blood clots that cause embolitic sequella, for example a stroke, at distant locations in the body. While using a single implant with walls that do not have slits may alleviate this problem, flow-reducing implants with non slit walls may not exhibit appropriate expansion capabilities and/or facilitate in situ revision of its configuration.

0186<figref idref="DRAWINGS">FIG. 8E</figref> is an isometric view of a dual layer flow-reducing implant <b>1400</b> in accordance with an exemplary embodiment of the invention. In an exemplary embodiment, dual layer flow-reducing implant <b>1400</b> comprises a first flared section <b>1450</b> and/or a second flared section <b>1460</b>. For purposes of clarity, the components of flare <b>1460</b>, alone, will be focused on, though similar features can be applied to flared section <b>1450</b>.

0187In an exemplary embodiment, dual layer flow-reducing implant <b>1400</b> comprises a flared section <b>1460</b> comprising an external cone <b>1420</b> and an internal cone <b>1410</b>. Internal cone <b>1420</b>, for example, comprises slits <b>1422</b> and <b>1426</b> and external cone <b>1410</b> comprises slits <b>1412</b> and <b>1416</b> so that cones <b>1410</b> and <b>1420</b> can be transported to an implantation site in a non-expanded state and expanded at the implantation site.

0188Further expansion of cone <b>1410</b> and/or <b>1420</b> may be desirable and can be incorporated into their respective designs so that cone <b>1410</b> and/or <b>1420</b> expand to a first diameter when pressed radially outward by a balloon catheter at a first expansion pressure. Cone <b>1410</b> and/or <b>1420</b> can then expand to a second, greater, diameter when pressed radially outward by a balloon catheter at a second, greater, expansion pressure.

0189In an exemplary embodiment, when slits <b>1422</b> and <b>1426</b> are aligned with slits <b>1412</b> and <b>1416</b> respectively, blood flows in a direction <b>1451</b> (e.g., in a space <b>132</b> shown in <figref idref="DRAWINGS">FIG. 1</figref>) and through slits <b>1432</b> and <b>1436</b>. With alignment of slits <b>1412</b> with <b>1422</b> and/or slits <b>1416</b> with <b>1426</b>, flow-reducing implant <b>1400</b> may be implanted into a vessel with a relatively slow flow speed and/or low pressure. For example, with implantation in the coronary sinus narrow area <b>1440</b> may fill with tissue that aids in anchoring implant <b>1400</b> without risk of an embolism.

0190Alternatively or additionally, as there is limited or cessation of flow into space <b>132</b>, a clot forms in area <b>1440</b> and stabilizes in its position. Stabilized clot in area <b>1440</b> becomes incorporated into the surrounding tissue and against dual cone flow-reducing implant <b>1400</b> so that it is further stabilized in its position.

0191In an exemplary embodiment, slits <b>1422</b> and <b>1426</b> can be rotated, prior to implantation, in relation to slits <b>1412</b> and <b>1416</b> so that blood flow in direction <b>1451</b> is substantially stopped to various degrees. With misalignment of slits <b>1422</b> and <b>1426</b>, reducing implant <b>1400</b> may be implanted into a vessel with a relatively higher flow speed and/or higher pressure, for example a main trunk of an artery thereby protecting the patient against the dangers of embolism migration.

0192The alignment of slits <b>1422</b> and <b>1426</b> is optionally set prior to implantation in a blood vessel in relation to slits <b>1412</b> and <b>1416</b>, in order to establish a pre-defined blood flow pattern, and the two layers expanded or allowed to expand, together. To ensure that cones <b>1410</b> and <b>1420</b> remain fixed in position in relation to each other, cones <b>1410</b> and/or <b>1420</b> have, for example, a friction surface interface and/or interdigitation. Alternatively or additionally, the two layers may be deployed in different ways, for example, the inner layer may be plastically deployed and the outer layer self-deployed. Possibly, the profile of the two layers does not match along its entire length. Alternatively or additionally, the outer layer is plastically deformed by a self-deploying inner layer (which self deployment may also provide the friction for locking). Alternatively or additionally, cone <b>1420</b> may be rotated, for example using a suitable internal engaging catheter, after implantation

0193The flared sections <b>1450</b> and <b>1460</b> need not be symmetric. For example, the implant may also selecting between flow blockage at one section, the other and optionally both. Flow only into space <b>132</b>, may assist in clot formation. Flow only out of space <b>132</b> may assist in collapsing a surrounding blood vessel,

0194<figref idref="DRAWINGS">FIGS. 9A-9G</figref> illustrate various flow-reducing implant variations, in accordance with exemplary embodiments of the invention. While a sigmoid-like flare is shown, a linear or other flared design may also be provided.

0195<figref idref="DRAWINGS">FIG. 9A</figref> is a flow-reducing implant <b>900</b> with having a narrowed section <b>902</b> and a single flared section <b>904</b>. Narrowed section <b>902</b> may point upstream or down stream. One potential advantage of this design is that the delivery system is less likely to get caught inside narrowed section <b>902</b>. Another potential advantage is that a completely obstructing implant can be provided. In an exemplary embodiment of the invention, however, even such a completely obstructing implant has smooth sides, to prevent damage to the coronary sinus. Possibly, the outer diameter of the completely obstructing implant or a nearly complete flow-reducing implant is increased beyond that of the coronary sinus, to prevent dislodgment of the implant. Alternatively or additionally, one or more barbs on the outside of the implant may be provided. Optionally, a cone shaped flow-reducing implant is provided with one or more openings for blood flow on the face of the cone, rather than at its apex as shown.

0196Alternately to a plain flow-reducing implant, the narrowing may be a valve, for example, a valve that opens, to a full or partial diameter, after a suitable pressure is achieved in the coronary sinus distal from the right atrium. For example, a leaflet valve or other type of vascular valve as known in the heart may be provided.

0197<figref idref="DRAWINGS">FIG. 9B</figref> shows an alternative flow-reducing implant <b>910</b>; with two narrowed sections <b>912</b> and <b>916</b> sandwiching a flared section <b>914</b> between them, in accordance with an exemplary embodiment of the invention. Optionally, the different narrowed sections have a different inner diameter. Optionally, the narrowed sections are selectively expanded using a balloon to achieve a desired pressure profile.

0198<figref idref="DRAWINGS">FIG. 9C</figref> is an alternative flow-reducing implant <b>920</b> with three narrowed sections <b>922</b>, <b>926</b> and <b>929</b> and two flared sections <b>924</b> and <b>928</b> between the narrowed sections, in accordance with an exemplary embodiment of the invention.

0199Certain blood vessels may exhibit a taper along their length, for example forming an angle <b>1310</b>, shown in <figref idref="DRAWINGS">FIG. 9D</figref>. Vessels that change in size along their length may occur, for example, in the coronary sinus as it joins into the right atrium. In a tapered blood vessel it may be desirable to utilize a tapered-type flow-reducing implant <b>930</b> (<figref idref="DRAWINGS">FIG. 9E</figref>), seen in detail in <figref idref="DRAWINGS">FIG. 9D</figref>, in accordance with exemplary embodiments of the invention.

0200<figref idref="DRAWINGS">FIG. 9D</figref> is an isometric view of an exemplary embodiment of a tapered flow-reducing implant <b>1300</b>, (with a similar configuration to implant <b>930</b>) in accordance with an exemplary embodiment of the invention. Tapered flow-reducing implant comprises a smaller flared section <b>1330</b>, a narrowed section <b>1340</b> and larger flared section <b>1320</b>. The size of smaller flared section <b>1330</b>, for example, is governed one or more slits <b>1342</b> that are transverse to the axis of narrowed section <b>1340</b> and one or more slits <b>1346</b> that are longitudinal to the axis of narrowed section <b>1340</b>.

0201The size of larger section <b>1320</b> is governed, for example, by two or more slits <b>1322</b> that are transverse to the axis of narrowed section <b>1340</b> and/or two or more slits <b>1320</b> that are longitudinal to the axis of narrowed section <b>1340</b>.

0202Optionally, slits <b>1342</b>, <b>1346</b>, <b>1322</b> and/or <b>1326</b>, be varied size and/or configuration to govern the shape of flared sections <b>1320</b> and/or <b>1330</b>. Alternatively or additionally, slits <b>1342</b>, <b>1346</b>, <b>1322</b> and/or <b>1326</b> may be have various arrangements to provide different contours to flared sections <b>1320</b> and/or <b>1330</b> and/or narrowed section <b>1340</b>.

0203While openings <b>1330</b> and <b>1320</b> are shown as being round, they may have a variety of configurations to conform to different vessel configurations as noted above. Further, the ratio between opening <b>1330</b> and <b>1320</b> may be varied to conform to any vessel diameter where flow-reducing implant <b>1300</b> is implanted. As in other figures, the material of the implant is shown distorted, while in some embodiments, it may be the slits, possibly in addition to the material, which is distorted.

0204<figref idref="DRAWINGS">FIG. 9E</figref> is a tapered flow-reducing implant <b>930</b> in which one flared section <b>932</b> has a smaller diameter than a second flared section <b>936</b>, but larger than an intermediate narrowed section <b>934</b>, in accordance with an exemplary embodiment of the invention.

0205In <figref idref="DRAWINGS">FIG. 9F</figref> is a flow-reducing implant <b>940</b> that is not axially and/or rotationally symmetric around its axis, in accordance with an exemplary embodiment of the invention. In an exemplary embodiment, a first flared section <b>946</b> is distorted relative to an axis defined by a second flared section <b>942</b> and a narrowed section <b>944</b>.

0206Optionally, flow-reducing implant <b>940</b> is curved. In an exemplary embodiment of the invention, asymmetric or curved flow-reducing implants include special markings, for example, radio-opaque or radio-transparent areas, to assist correct orientation of flow-reducing implant <b>940</b> in a blood vessel.

0207<figref idref="DRAWINGS">FIG. 9G</figref> is a flow-reducing implant <b>950</b>, in which a narrowed section <b>954</b> is a sleeve <b>954</b>, in accordance with an exemplary embodiment of the invention. Sleeve <b>954</b>, for example, is formed of a flexible graft material, such as Dacron or GoreTex. Flow-reducing implant <b>950</b> further comprises at least one of two outer rings <b>952</b> and <b>956</b> that serve to anchor flow-reducing implant <b>950</b> in the blood vessel. A potential advantage of using a sleeve is that it can bend to conform to the vein geometry and/or dynamics. Other flow-reducing implant designs can also bend. Optionally, the graft material is elastic, so it can serve as a pressure limiting valve, to better control coronary sinus pressure. Optionally, a constraining ring is provided on the outside of section <b>954</b>, to restrict the lumen of flow-reducing implant <b>950</b>. Optionally, the ring is placed on flow-reducing implant <b>950</b> during the procedure, to achieve a desired narrowing effect. Alternatively or additionally, the ring is expandable, for example using a balloon, to allow controlling the narrowed section of flow-reducing implant <b>950</b>. Optionally, the ring is sutured to narrowed section <b>954</b>. Optionally, section <b>954</b> is stiffened, for example, using a wire, as known in the art of stent-grafts.

0208In an exemplary embodiment of the invention, flow-reducing implant <b>100</b> is provided in kit form, possibly with a delivery system, a flow-reducing implant diameter control system, additional flow-reducing implants, external bands and/or other means for reducing its inner diameter, and including instructions for use and/or size markings. Optionally, flow-reducing implant <b>940</b> is provided inserted into a delivery system or packaged with a delivery system.

0209As noted above, in some embodiments of the invention a flow reducing implant is constrained by providing a band on the outside of the implant.

0210<figref idref="DRAWINGS">FIGS. 10A-10B</figref> are an isometric view and detail, respectively, of a ringed mesh-type flow reducing implant embodiment, in accordance with an exemplary embodiment of the invention. In an exemplary embodiment, mesh-type flow-reducing implant <b>1500</b> (<figref idref="DRAWINGS">FIG. 10A</figref>) comprises a flare shoulder <b>1502</b> and/or a flare shoulder <b>1504</b> that are relatively long in length, for example, to increase the area of contact between flow-reducing implant <b>1500</b> and surrounding vessel walls. Alternatively or additionally, tissue may grow through the mesh of flare shoulders <b>1502</b> and/or <b>1504</b>, providing good anchorage of mesh-type flow-reducing implant <b>1500</b>. Optionally, mesh-type flow-reducing implant <b>1500</b> comprises and/or is coated with materials that promote tissue ingrowth. A rim <b>1620</b>, which may be, for example jagged or smooth is also optionally provided on each shoulder.

0211Optionally, the initial shape of mesh-type flow-reducing implant <b>1500</b> is governed by one or more bands <b>1522</b> and/or <b>1524</b> that constrict an area <b>1528</b> of mesh-type flow-reducing implant <b>1500</b>. In an exemplary embodiment, the surrounding tissue collapses onto mesh-type flow-reducing implant <b>1500</b> to reduce blood flow through the walls of constriction area <b>1528</b>. While two bands <b>1522</b> and <b>1524</b> are shown, a single band, for example band <b>1522</b> alone, may be used to create constriction area <b>1528</b>.

0212In an exemplary embodiment, an operator manually tying their ends together, prior to implantation, adjusts the rings formed by band <b>1522</b> and/or <b>1524</b> in circumference, for example. Adjustment of band <b>1522</b> and/or <b>1524</b> prior to implantation allows the operator to establish constriction area <b>1528</b> with a specific size to reduce blood flow and thereby promote angiogenesis. Alternatively or additionally, a balloon catheter, for example, is expanded in area <b>1562</b> to cause expansion of bands <b>1522</b> and/or <b>1524</b>, thereby expanding area <b>1562</b> to increase blood flow there through. In this fashion, blood reduction through flow-reducing implant <b>1500</b> can be regulated prior to placement and/or following placement of flow-reducing implant <b>1500</b> in a blood vessel.

0213In an exemplary embodiment, band <b>1524</b> rips when a large expansion force is placed against it. To adjust the diameter of area <b>1528</b> following implantation, a balloon catheter is positioned inside area <b>1562</b> and expanded until the pressure exceeds that which is required to rip band <b>1524</b>. With band <b>1524</b> ripped, the area of mesh area <b>1562</b> directly under it expands so that area <b>1562</b> expands in diameter so that it has the diameter of ring <b>1522</b>.

0214Optionally, band <b>1524</b> has a smaller diameter than band <b>1522</b>, providing two levels of expansion. For example, so that as a balloon catheter is expanded to a first diameter, it expands smaller diameter band <b>1524</b>, increasing the diameter of constriction area <b>1528</b> to a first expanded diameter. Should further increase in flow be desired, a balloon catheter is expanded to a second diameter and expands larger diameter band <b>1524</b> and/or smaller diameter band <b>1524</b>, increasing the diameter of constriction area <b>1528</b> to a second expanded diameter.

0215Ring <b>1524</b> has, for example, a diameter of 6 millimeters while ring <b>1522</b> has a diameter of 8 millimeters so that area <b>1562</b> has flow passage of 6 millimeters. By expanding an expansion balloon inside area <b>1562</b> and causing ring <b>1524</b> to rip, the area under ring <b>1524</b> expands. However, ring <b>1522</b>, with its diameter of 8 millimeters, maintains its integrity. Hence area <b>1562</b> now has a flow passage of 8 millimeters (less the thickness of the mesh or other material from which the implant is formed.

0216<figref idref="DRAWINGS">FIG. 10B</figref> is a detail of an embodiment of ring <b>1522</b> comprising an adjustable band <b>1540</b> that forms ring <b>1522</b> and is held at a specific diameter by a clasp <b>1544</b>. Alternatively or additionally, adjustable band <b>1540</b> is maintained at a specific diameter by a clasp <b>1546</b>. In an exemplary embodiment, clasps <b>1544</b> and/or <b>1546</b> hold adjustable band <b>1540</b> so that during implantation, ring <b>1522</b> remains at a specific diameter until, for example, an expanding balloon catheter is expanded against adjustable band <b>1540</b> and the diameter of ring <b>1522</b> is expanded. In an exemplary embodiment, clips <b>1544</b> and <b>1546</b> comprise, for example, a nylon material that holds band <b>1522</b> at a specific diameter and allow expansion of the diameter only under expansion pressure from, for example, a balloon catheter. Optionally, two clasps are provided, so no part of band <b>1540</b> sticks out from the ring. In an exemplary embodiment of the invention, the clasps are “C” shaped and band <b>1540</b> optionally include bumps that prevent sliding of the band through the clasps. Alternatively or additionally, friction prevents such sliding.

0217In an exemplary embodiment, flare shoulders <b>1504</b> and/or <b>1502</b> are 0.5 centimeters to 1 centimeter in length through they could be less than 0.5 centimeters or greater than 1 centimeter in length, for example, depending upon vessel configuration.

0218In an exemplary embodiment, mesh-type flow-reducing implant <b>1500</b> comprises strands that form its mesh comprising gortex, Dacron and/or steel. Further, the material comprising the mesh can be configured to be flexible or rigid, depending, for example, on the materials, its thickness, based upon, for example the flow dynamic dynamics desired.

0219<figref idref="DRAWINGS">FIG. 11</figref> is an isometric view of a partially covered mesh-type flow reducing implant embodiment <b>1600</b>, in accordance with an exemplary embodiment of the invention. Mesh-type flow reducing implant <b>1600</b> comprises a covering <b>1614</b> over or inside narrow section <b>1624</b>, implanted in a blood vessel <b>1680</b>, shown in cross section. In an exemplary embodiment, mesh-type flow reducing implant <b>1600</b> comprises one or more flare shoulders <b>1602</b> that contact blood vessel <b>1680</b> to provide anchoring. A rim <b>1620</b>, which may be, for example jagged or smooth is also optionally provided on each shoulder.

0220Alternatively or additionally, mesh-type flow reducing implant <b>1600</b> comprises a covering <b>1614</b> the restricts blood flow through the surface of flow reducing implant <b>1600</b> and/or blood turbulence in an area of constriction <b>1624</b>, thereby reducing danger of embolitic migration problems.

0221In an exemplary embodiment of the invention, covering <b>1614</b> comprises a separate, flexible layer, that is attached to flow reducing implant <b>1600</b> at several points (e.g., at constriction area <b>1624</b> and/or flare shoulders <b>1602</b>) to prevent tearing when implant <b>1600</b> expands. Prior to expansion, for example, covering <b>1614</b> is folded and/or pleated. Alternatively or additionally, covering <b>1614</b> has a low bulk and, for example, is integrated into flow reducing implant <b>1600</b> structure, for example, so that it substantially spans the open areas of the mesh. Examples of materials comprising covering <b>1614</b>, include gortex, latex and/or silicone, on the inside and/or outside of flow reducing implant <b>1600</b>.

0222<figref idref="DRAWINGS">FIG. 12</figref> is an isometric view of a sheath-type flow reducing implant <b>2340</b>, in accordance with an exemplary embodiment of the invention. Sheath-type flow reducing implant <b>2340</b> comprises a sheath <b>2342</b> that encircles at least a portion of outer wall <b>102</b>. Sheath-type flow reducing implant <b>2340</b> with a single sheath <b>2342</b> differs from implant <b>950</b> (shown <figref idref="DRAWINGS">FIG. 9G</figref>) in which a narrowed section <b>954</b> is shown with two flared sides and supported by stents or rings <b>952</b> and/or <b>956</b>. Connected to sheath <b>2342</b> and/or an extension thereof is a sheath projection <b>2352</b>, with an opening <b>2354</b> to allow passage of blood flow via lumen <b>2216</b>. Sheath projection <b>2352</b>, for example, can be configured with grooves and/or projections to further control the amount of obstruction of the central blood flow stream. In an exemplary embodiment of the invention, sheath <b>2352</b> includes a stiffener ring which maintains its opening patent. Alternatively or additionally, one or more stiffening axial or radial struts are provided to assist in maintaining the shape of sheath <b>2352</b>.

0223<figref idref="DRAWINGS">FIG. 13</figref> is longitudinal section of an inflatable tube-type flow reducing implant <b>2400</b>, in accordance with an exemplary embodiment of the invention. Inflatable tube-type flow reducing implant <b>2400</b> comprises a long wall <b>2406</b>, a portion of which is surrounded by a ring-shaped tube <b>2420</b>. Optionally, tube <b>2420</b> can be located along any portion of long wall <b>2406</b> and/or of any configuration that reduces blood flow through lumen <b>2114</b>. In an exemplary embodiment of the invention, tube <b>2420</b> replaces the function of ring <b>1522</b> of <figref idref="DRAWINGS">FIG. 10A</figref>.

0224In an exemplary embodiment, tube <b>2420</b> has an interior space <b>2430</b> enclosed within a circular wall <b>2402</b> that is, for example, inflatable using a hose <b>2428</b>. In an exemplary embodiment, tube <b>2420</b> inflates so that interior <b>2430</b> has two or more cross sectional diameters, thereby allowing adjustment of narrow lumen <b>2114</b> to modify the amount of reduction in blood flow. Hose <b>2428</b> is optionally removed or torn off after deployment. Alternatively or additionally, hose <b>2428</b> may be attached after deployment, for example having a needle tip used to inject fluid into tube <b>2420</b>. Alternatively or additionally, tube <b>2420</b> may be torn or punctured after implantation, to increase the diameter of the narrowing.

0225Alternatively or additionally, tube interior <b>2430</b> contains a material that absorbs liquid, thereby expanding. Following implantation, for example, tube <b>2420</b> absorbs liquid and interior <b>2430</b> increases in size until tube <b>2420</b> reaches its expanded state.

0226Alternatively or additionally, wall <b>2402</b> and/or tube <b>2430</b> comprise a resilient material, for example Nitinol, and expand to a final state without inflation. Alternatively or additionally, flow-reducing implant <b>2400</b>, and/or embodiments mentioned below, are manufactured from a biocompatible material, comprising, for example, a soft silicone elastomer and/or another soft material such as latex, Teflon, gortex, Kevlar and/or polyurethane.

0227Alternatively or additionally, interior <b>2430</b> is filled, for example with a spongy material, for example that is different from the material comprising long wall <b>2406</b> and/or wall <b>2402</b>. Spongy material of interior <b>2430</b>, for example, remains compressed in a compact size until its exit from catheter <b>2122</b> whereupon interior <b>2430</b> expands, causing the expansion of tube <b>2420</b>.

0228In an exemplary embodiment, long wall <b>2406</b> is contoured and comprises a shape memory material and achieves its final state, including a bulge <b>2404</b>, upon exit from catheter <b>2122</b>. Alternatively or additionally, long wall <b>2406</b> is, for example, not contoured and tube <b>2420</b> presses against long wall <b>2406</b> to create bulge <b>2404</b>.

0229In an alternative embodiment of the invention, wall itself <b>2406</b> comprises a balloon, which is inflated. Alternatively or additionally, wall <b>2406</b> is manufactured with a varying thickness, for example being made of a flexible plastic cylinder with its top and bottom reamed out.

0230<figref idref="DRAWINGS">FIG. 14</figref> is a longitudinal section of a flow reducing implant with shape-conforming elements <b>2700</b>, in accordance with an exemplary embodiment of the invention. Shape-conforming element implant <b>2700</b> comprises one or more shape-conforming elements <b>2720</b> and/or <b>2722</b> that can be remotely induced to change their configuration. Remote control of the configuration of elements <b>2720</b> and/or <b>2722</b> causes, for example, change in configuration, constriction and/or expansion of narrow lumen <b>2742</b>, flare <b>2744</b> and/or flare <b>2746</b> without associated hazards of an invasive procedure. As narrow lumen <b>2742</b>, flare <b>2744</b> and/or flare <b>2746</b> change their configuration; the blood flow is obstructed to a greater or lesser extent, thereby promoting angiogenesis.

0231Shape-conforming elements <b>2720</b> and/or <b>2722</b>, for example, are charged so that as they receive impulses from impulses <b>2730</b> and/or <b>2732</b>, they change into one or more different geometric shapes and/or configurations. The shapes of elements <b>2720</b> and/or <b>2722</b> induced by impulsers <b>2730</b> and <b>2732</b> changes the reduction in blood flow, thereby influencing angiogenesis.

0232For example, one or both shape-conforming elements <b>2720</b> and/or <b>2722</b> straighten, they exert outward expansion pressure on narrow lumen <b>2742</b>, thereby allowing blood flow there through to increase. When one or both shape-conforming elements <b>2720</b> and/or <b>2722</b> bend further than depicted in <figref idref="DRAWINGS">FIG. 14</figref> they pull the walls of narrow lumen <b>2742</b> inward, causing lumen <b>2742</b> to narrow, thereby reducing blood flow there through.

0233Alternatively or additionally, when shape-conforming elements <b>2720</b> and/or <b>2722</b> bend or straighten wall <b>2102</b> along narrow lumen <b>2742</b> may change the obstruction of the lumen by wall <b>2102</b> to influence angiogenesis.

0234Alternatively or additionally, shape-conforming elements <b>2720</b> and/or <b>2722</b> are located exterior to flow-reducing implant <b>2700</b>, for example along outer wall <b>2102</b>. Alternatively or additionally, other shape-conforming elements <b>2720</b> and/or <b>2722</b> may be located along flares <b>2744</b> and/or <b>2746</b> to provide additional and/or alternative remote control of flow-reducing implant <b>2700</b>.

0235Optionally, impulses provided by impulsers <b>2730</b> and <b>2732</b> to induce changes in shape-conforming elements <b>2720</b> and/or <b>2722</b> and comprise one or more of: RF, acoustic waves such as ultrasound and/or low frequency sound, heat, electricity, electromagnetic, radiation. Alternatively or additionally, impulsers <b>2730</b> and <b>2732</b> mediate a chemical reaction that modifies elements <b>2720</b> and/or <b>2722</b>, thereby changing their configuration.

0236In an exemplary embodiment, a director <b>2738</b>, external to the patient, directs impulsers <b>2730</b> and <b>2732</b> to provide impulses to shape-conforming elements <b>2720</b> and/or <b>2722</b>, thereby causing the changes in geometric shape. Director <b>2738</b>, for example, directs impulsers <b>2730</b> and <b>2732</b> via radio waves from an antenna <b>2758</b>. Impulses <b>2730</b> may be, for example ratchet mechanisms or motors powered or stimulated by such signals, to shorten bands that surround the implant. In an exemplary embodiment of the invention, impulsers <b>2730</b> comprise one or more magnetic motors that include a magnetic gear which is turned by the effect of a rotating magnetic field applied outside the body and which taming causes a tightening of a band (e.g., <b>2722</b>, <b>2720</b>).

0237Alternatively or additionally, elements <b>2720</b> and/or <b>2722</b> are sensitive to waves that are propagated external to the patient. For example, director <b>2738</b> provides one or more of: RF, acoustic waves such as ultrasound and/or low frequency sound, heat, electricity, electromagnetic and radiation to influence the configuration of elements <b>2720</b> and/or <b>2722</b>. Impulsers <b>2730</b> and <b>2732</b> may then be optional, or be used only to provide a ratchet mechanism.

0238In an exemplary embodiment, shape-conforming elements <b>2720</b> and/or <b>2722</b> comprise a material with a positive charge, for example positively charged plastic and/or silicone rubber. Alternatively or additionally, shape-conforming elements <b>2720</b> and/or <b>2722</b> comprise a negatively charged material.

0239Optionally, shape-conforming elements <b>2720</b> and/or <b>2722</b> are manufactured from a material comprising charged lithium ions. In an exemplary embodiment, waves cause the charged lithium ions to align, thereby changing the geometry of shape-conforming elements <b>2720</b> and/or <b>2722</b> to cause changes in the shape of outer wall <b>2102</b> and/or inner wall <b>2104</b>.

0240In an exemplary embodiment, the strength and/or length of impulses aid in changing shape-conforming elements <b>2720</b> and/or <b>2722</b>. For example, impulsers <b>2730</b> and <b>2732</b> provide an electric impulse of between 0.1 volts and 0.5 volts (optionally, 0.1 volts or less or 0.5 volts or more), for a period of 10 msec or longer or 6 msec. or shorter. The factors influencing the impulse chosen, for example, depend upon materials comprising shape-conforming elements <b>2720</b> and/or <b>2722</b>, their responsiveness to the impulses and/or the desired changes in their shapes to influence the shape of flow-reducing implant <b>2700</b>.

0241Flow-reducing implant <b>2700</b>, with shape-conforming elements <b>2720</b> and/or <b>2722</b> allows modification in shape and/or blood flow reduction following implantation of flow-reducing implant <b>2700</b> in coronary sinus <b>2110</b> without an invasive procedure. Alternatively or additionally, an embodiment of shape-conforming element implant <b>2700</b> that assumes its installed shape without, for example, the use of balloon catheter <b>1000</b> may be desirable.

0242In an alternative embodiment, externally applied RF radiation is received by threads <b>2722</b> and <b>2720</b>, which act as antenna and heat up, thereby expanding. Alternatively or additionally, such heating is used to inflate a balloon band, for example by causing an irreversible chemical reaction that releases gas.

0243<figref idref="DRAWINGS">FIG. 15</figref> is a plan layout of a cord-type flow reducing implant <b>2900</b>, in accordance with an exemplary embodiment of the invention. In an exemplary embodiment, cord-type flow-reducing implant <b>2900</b>, comprises a preformed shape that will easily spring into its installed shape without, for example, use of balloon catheter. Alternatively, a balloon based expansion mechanism is provided. In an exemplary embodiment, one or more edges <b>2910</b> are joined to one or more edges <b>2908</b> to form cord-type flow-reducing implant into a tubular shape with lumen <b>806</b> passing there through.

0244In its assembled state, cord-type flow-reducing implant <b>2900</b> comprises a row of slits <b>2924</b> through which a cord <b>2954</b> passes, that is modified with minimal expansion pressure from balloon catheter.

0245In an exemplary embodiment, cord <b>2954</b> is woven to pass under a lead post <b>2982</b> and over a trailing post <b>2986</b> so that cord <b>2954</b> is woven across cord-type flow-reducing implant <b>2900</b>. Alternatively or additionally, cord <b>2954</b> is expandable and attached to surfaces of slots <b>2924</b>, for example their surfaces facing lumen <b>2806</b> or their opposite (outside) surfaces. Optionally, the cord blocks blood flow through the wall of the reducer.

0246In an exemplary embodiment, after cord-type flow-reducing implant <b>2900</b> expands to its initial configuration automatically upon exiting a delivery sheath. When further size modification is required, a balloon catheter is introduced into the interior of cord-type flow-reducing implant <b>2900</b>. The balloon catheter is inflated, for example, between 3-4 atmospheres (optionally, 3 atmospheres or less or 4 atmospheres or more), to cause cord <b>2954</b> to expand (or it may be loose) radially outward, thereby allowing slit <b>2958</b> to expand further and the diameter of the adjacent flared section to increase.

0247Alternatively or additionally, at least a portion of an edge <b>2910</b> is detached from at least a portion of an edge and at least a portion edge <b>2910</b> and edge <b>2908</b> overlap. When expansion is required, expansion force is applied, for example, between 7-8 atmospheres (optionally, 7 atmospheres or less or 8 atmospheres or more) is applied. Cord <b>2954</b>, in response to the pressure, elongates (or is loose and tightens) so that edge <b>2910</b> draws closer and/or passes edge <b>2908</b>, allowing cord-type flow-reducing implant <b>2900</b> to attain another, expanded, diameter.

0248In an exemplary embodiment, cord <b>2954</b> comprises a plastic material that stretches to two or more lengths, depending upon the expansion pressure that is applied to it. Hence, at a lower pressure, cord <b>2954</b> expands to a first length, thereby defining a first narrow diameter of cord-type flow-reducing implant <b>2900</b>. Subsequently a second expansion pressure is applied and cord <b>2954</b> attains a second, longer, length, thereby defining a second diameter, wider than the narrow diameter.

0249Alternatively or additionally, cord-type flow-reducing implant <b>2900</b> includes one or more diameters in which edge <b>2910</b> and edge <b>2908</b> are separated by a space, thereby providing an interrupted lumen surface. Alternatively or additionally, cord <b>2954</b> severs upon application of, for example, pressure between 9-10 atmospheres (optionally 9 atmospheres or less or 10 atmospheres or more). Upon severing cord <b>2954</b>, edge <b>2910</b>, for example, maximally separates from edge <b>2908</b>; thereby applying unrestricted pressure against coronary sinus <b>2110</b>.

0250In an exemplary embodiment, cord <b>2954</b> of flow-reducing implant <b>2900</b> comprises a biocompatible material that dissolves in the environment of coronary sinus <b>2110</b>, for example, a material comprising galactic acid and/or polygalactic acid and/or other materials with similar properties. In an exemplary embodiment, flow-reducing implant <b>2900</b> is placed in coronary sinus <b>2110</b> and the balloon catheter is used to expand it so that its outer surface contacts the inside surface of coronary sinus <b>2110</b>. Over a period of time, for example cord <b>2954</b> degrades, depending upon the biodissolvable material comprising cord <b>2954</b>. (Optionally, degradation of cord <b>2954</b> occurs in less than three days or more than three days, dependent upon its composition and/or desired duty cycle.) Once cord <b>2954</b> has dissolved, flow-reducing implant <b>2900</b> retains and/or assumes a shape with its outer surface in contact with the inner surface of coronary sinus <b>2110</b>.

0251With cord <b>2954</b> dissolved, further expansion of inner diameter of flow-reducing implant <b>2900</b> is accomplished with balloon <b>1010</b> at a low atmospheric pressure due to the fact that edge <b>2908</b> passes edge <b>2910</b> without the hindrance of cord <b>2954</b>. Hence, to cause edge <b>2908</b> to pass edge <b>2910</b>, expansion force need only overcome the stiffness of the material comprising flow-reducing implant <b>2900</b>. In an exemplary embodiment, a pressure of between 3-4 atmospheres (optionally 3 atmospheres or less or 4 atmospheres or more), causes expansion of wall the lumen through flow-reducing implant <b>2900</b>.

0252In an exemplary embodiment of the present invention, flow-reducing implant <b>2900</b> comprises cord <b>2954</b> passing through slits <b>2924</b> and a cord <b>2964</b> passing through slots <b>2988</b>. Alternatively or additionally, flow-reducing implant <b>2900</b> comprises three or more cords: <b>2954</b>, <b>2964</b> at either end and a cord <b>2974</b> passing through slots <b>2926</b> substantially in the middle of flow-reducing implant <b>2900</b>.

0253Cords <b>2954</b>, <b>2964</b> and/or <b>2974</b> serve to maintain the shape and/or appropriate lumen diameter following installation. To expand the lumen through flow-reducing implant <b>2900</b>, balloon catheter <b>1000</b> is used to expand and/or sever cords <b>2954</b>, <b>2964</b> and/or <b>2974</b>. Alternatively or additionally, sever cords <b>2954</b>, <b>2964</b> and/or <b>2974</b> are biodissolvable, dissolving in the environment of coronary sinus <b>2110</b>.

0254It should be noted that when implant <b>2900</b> is deployed, the final shape is that of a cone, the relative lengths <b>2948</b>, <b>2938</b> and <b>2928</b> of the slits <b>2946</b>, <b>2936</b> (and <b>2934</b>) and <b>2926</b>, respectively, generally define the geometry of the expanded device. As shown, the cone shape is convex. However, other shapes, for example, concave may be provided instead. Also shown in this embodiment is that the slits are staggered, so that the expansion will be generally distributed over the surface of the implant.

0255While the above has been described for use in coronary veins, a flow reducing implant with similar design may also be used in other veins, for example, popliteal, tibial or saphenous veins. In an exemplary embodiment of the invention, described in greater detail below, one or more flow reducing implants are implanted in popliteal veins, to increase back-pressure and possibly enhance tissue perfusion pressure and/or redistribute blood flow in the leg. It is expected that pooling will not occur due to the existence of alternative drainage paths in the leg. Multiple insertions of flow reducing implants may be used to treat and/or hide varicose veins.

0256Within the closed facial compartments of the lower limb, a plurality of thin-walled, valved venae comitantes are subjected to intermittent pressure both at rest and during exercise. The pulsation of the adjacent arteries help to move the blood up the limb. Also, the contractions of the large muscles within the compartments during exercise compress these deeply placed veins and force the blood up the limb. The superficial saphenous veins, except near their termination, lie within the superficial fascia and are not subject to these compression forces. The valves in the perforating veins, which interconnect deep and surface veins, prevent the high-pressure venous blood from being forced outward into the low-pressure superficial veins. Moreover, as the muscles within the closed facial compartments relax, venous blood is sucked from the superficial into the deep veins. Lower limb venous pressure increases to dependency, stimulating a local sympathetic axon reflex, which triggers precapillary and arteriolar vasoconstriction. The resulting decrease in arterial calf inflow, known as the venoarterial response (VAR), is impaired in critical ischemia. The median VAR was found to be significantly lower in patients with stable claudication than in normal subjects or patients following successful revascularization (29.1 versus 59.5 and 63.9 percent respectively). Thus, patients with claudication apparently have a significant impairment of orthostatic sympathetic autoregulation. It should be mentioned that neovascularization is considered an important cause of venous reflux recurrences after ligation of foot veins. The pathogenesis of this phenomenon is so far obscure. It has been hypothesized that a hemodynamic factor could be the trigger initiating the process of neovascularization. In an exemplary embodiment of the invention, such a factor is provided in a form of increased pressure caused by reduction in vein diameter.

0257In an exemplary embodiment of the invention, the implantation of flow reducing implants in the veins is used to treat diabetic foot syndrome and/or varicose veins. In an exemplary embodiment of the invention, the blood vessels treated include a lower limb vein, for example a superficial vein such as the great or small saphenous veins or their tributaries, or a limb deep vein such as the anterior and posterior tibial or popliteal veins, or a limb perforating vein, such as those in the region of the ankle and the medial side of the lower part of the leg. The degree of reducing and/or size of the flow reducing implant may be the same as used for the coronary sinus and/or be adapted to fit the particular vein being treated.

0258In an exemplary embodiment of the invention, the implantation procedure is as described above for the coronary sinus, except, of course, that the flow reducing implant is conveyed to a leg vein, rather than to the coronary sinus, for example, via a femoral vein. Desirably, the flow reducing implant is implanted using a trans-vascular approach, for example, from the venous system. In an exemplary embodiment of the invention, the delivery system is inserted through a femoral vein to a deep lower limb vein, such as the popliteal vein or tibial vein. Once in the deep foot vein, the delivery system is guided (e.g., through a sharp bend) to the vein. Alternatively, for example, an open surgery approach may be used instead.

0259In a particular exemplary embodiment of the invention, a flow reducing implant is placed in a tibial vein and has a narrowing significant enough to encourage the formation of collateral circulation. It is hypothesized that collateral circulation is caused by an increase in venous blood pressure, which, in turn, increases the pressure in the capillaries and/or causes retro-flow in the capillaries and/or causes drainage of the capillaries. Alternative or additional hypotheses that are optionally used to select the constrictive effect of flow reducing implant include:

0260(a) the flow reducing implant increases the pressure in the foot capillaries, thus increasing perfusion duration;

0261(b) an increase in resistance of the venous system causes redistribution of blood flow in the ischemic foot; and

0262(c) increasing the arterial diastolic pressure (by restricting venous drainage) activates the sympathetic auto-regulation mechanism.

0263It should be noted that the selection of flow reducing implant may be made to achieve one or more of the above suggested effects, optionally to a desired degree and/or taking into account safety issues, such as allowing some drainage and maximum pressure allowed by the venous drainage system. These effects may be determined using various measurements, such as a pressure sensor on the implanting catheter.

0264In an exemplary embodiment of the invention, the selection of the flow reducing implant depends on one or more of:

0265(a) The lower limb vein length and diameter (e.g., to obtain a matching flow reducing implant geometry);

0266(b) Desired increase in the lower limb deep venous pressure before flow reducing implant, optionally including a maximum allowed pressure, for example, 50 mm Hg at which a peripheral vein expected to be damaged and/or fail (e.g., to decide what narrowing to select);

0267(c) Desired narrowing (e.g., to decide what narrowing to select);

0268(d) Desired later further narrowing (e.g., to decide on flow reducing implant type);

0269(e) Resistance of the lower limb vein wall (e.g., how elastic or stiff should flow reducing implant be and/or what inflation pressure to use);

0270(f) Desired redistribution of lower limb blood flow; and/or

0271(g) Desired retro-flow of blood in lower limb arteries and/or veins.

0272In an exemplary embodiment of the invention, the venous location of the flow reducing implant is selected to match various limb conditions, such as arterial blockage, alternatively or additionally to selecting the reducing diameter for each such flow reducing implant. Alternatively or additionally, the location(s) of implantation are selected to achieve a desired redistribution of lower limb artery pressures and/or blood flow, for example, to increase perfusion of ischemic or hibernating portions of the foot.

0273In an exemplary embodiment of the invention, the flow reducing implant implantation is combined with an arterial treatment, such as PCTA, stenosis removal (e.g., laser ablation) and/or stenting. The arterial treatment may be applied, for example, before, during or after the venous treatment, possibly during a same use of catheterization facilities. Doppler measurements are optionally used to asses leg perfusion. Alternatively or additionally, other perfusion and/or flow assessment methods may be used. Alternatively or additionally, an angiographic mapping is used before, during or after the procedure, for example to assist in determining what size flow reducing implant to use and/or a test obstruction of the lower limb vein. Such mapping may, for example, assist in determining a desired narrowing dimension of the flow reducing implant that will achieve a desired pressure increase and/or to detect possible side effects in the patient of such a pressure increase.

0274It is expected that one or more of the following effects is detected (at once and possibly to a greater extent after some delay): retrograde increase in the lower limb venous pressure, with a possible associated retrograde flow and/or improvement of perfusion in some ischemic areas.

0275It is expected that in some cases after a few weeks, the lower limb perfusion will increase and redistribution of blood flow will improve, even beyond the immediate result of the insertion of the flow reducing implant. Possibly, the autonomic auto-regulation mechanism of the venous flow will be reset and/or restart. After a few months, revascularization is expected, in some cases, to be well established, and significantly improve the clinical picture.

0276In another example, the flow reducing implant can be adapted to match other ducts or conduits in the body, for example, with respect to size, length, degree of narrowing, degree of elasticity and form of contact with the conduit walls.

0277In an alternative set of applications a flow reducing implant is used to reduce blood flow to a growth, for example a cancerous growth or other tumors.

0278A first example in the treatment of tumors is the uterus. The myometrium (inner lining of uterus) gives rise to a common tumor, a leiomyoma, which is a major source of abnormal uterine bleeding and a major indication for hysterectomy. The endometrial cavity is often the site of hyperplasia and neoplasia.

0279Uterine Leiomyomas, commonly known as fibroids or myomas, are well-circumscribed, benign tumors arising from the smooth muscle of the myometrium. They are composed of smooth muscle and extracellular matrix. Leiomyomas are the most common solid pelvic tumors in women. These are clinically apparent in 20% to 25% of women during the reproductive years, but careful pathologic inspection of the uterus reveals that they are present in more than 80% of women. Leiomyomas are characterized by their location in the uterus. Subserosal leiomyomas are located just under the uterine serosa and may be attached to the corpus by a narrow or a broad base. Intramural leiomyomas are found predominantly within the thick myometrium but may distort the cavity or cause an irregular external uterine contour. Submucous leiomyomas are located just under the uterine mucosa (endometrium). A known treatment is Uterine artery embolization in which small bubbles are freed in a supply vessel (e.g., a Uterine artery), causing embolisms in capillaries of the leiomyoma.

0280Interestingly, because the uterus receives branches from uterine and ovarian arteries, the uterus has a dual blood supply. The uterine artery is derived from the hypogastric anterior trunk. It crosses over the ureter at the level of the internal os of the cervix and divides into ascending and descending limbs. The ascending limb runs tortuously upward, between the leaves of the broad ligament, and supplies horizontal anterior and posterior branches to the cervix and the corpus. The descending branch of the uterine artery turns inferiorly and supplies the vagina from the lateral aspect. It anastomoses freely with the vaginal artery along its course. The ovarian arterial supply also has branches that anastomose with the ascending limb of the uterine artery.

0281In accordance with an exemplary embodiment of the invention, a leiomyoma is distinguished from healthy tissue by its degree of collateral vasculature and/or its sensitivity to ischemia.

0282In an exemplary embodiment of the invention, uterine fibroid tumors are treated by implanting a flow reducing implant in selected uterine arteries, thus causing a reduction of the arterial blood supply of the uterine fibroid tumor, leading to ischemia and gradual necrosis of the tumor.

0283In an exemplary embodiment of the invention, the procedure is as follows. With the patient under mild intravenous sedation and local anesthesia, a small angiographic catheter is introduced into the femoral artery and guided into the left uterine artery. Arteriography is performed, determining the arteries diameter. A flow reducing implant is then inserted into the artery, causing a narrowing of its diameter. The process is optionally repeated in the right uterine artery. The flow reducing implant reduces arterial blood flow through the uterine arteries and causing ischemic necrosis. Normal myometrium is possibly unharmed because multiple collateral arteries supply it. After the right and left uterine arteries are catheterized, the catheter is removed, and the patient optionally undergoes standard post-arteriographic monitoring and recovery. Optionally, the narrowed section reduces the vessel cross-section by 30%, 50%, 80%, 90% or any other lower, larger or intermediate amount, or even completely occludes the vessel. For example, the narrowed section may have an inner diameter of 0.3 mm, 0.5 mm, 1 mm or any larger, smaller or intermediate size.

0284As with the coronary application described above, a uterine procedure can be minimally invasive (e.g., using a laparoscope or a catheter), or be applied while performing other surgery.

0285Another application is treating cancer. In a known treatment of liver cancer, a viscous material is injected into a supply vessel of liver cancer, then a chemical poison is injected and then the vessel is sealed. However, the use of viscous material has various associated dangers, such as causing embolism in the brain and lungs.

0286In an exemplary embodiment of the invention, a flow reducing implant is used for treating cancer, especially cancer of the liver, for example, isolated liver metastases and for hepatocellular carcinoma and/or other tumors including HCC, colorectal, neuroendocrine, leiomyosarcoma, and melanoma metastases.

0287In an exemplary embodiment of the invention, malignant tumors are treated by implanting a flow reducing implant in selected arteries that supply the malignant tumors, thus causing a significant reduction of arterial blood to the tumor, leading to tumor-cell hypoxia. This results in a controlled tumor regional ischemia and infarct and subsequent necrosis of tumors in the infarcted region. Optionally, various chemical treatments, such as known in the art are used as well.

0288The liver is apparently especially amenable to this approach, due to the distinct lobular anatomy of the liver. Another potential factor is the existence of two independent blood supplies to the liver. A further potential factor is the ability of healthy hepatic tissue to compensate for tissue mass lost.

0289In an exemplary embodiment of the invention, the procedure is as follows. Under local anesthesia and mild sedation, a superselective catheter is inserted via a selected artery and threaded into the desired artery supplying the tumor, for example into the hepatic artery. Angiography is then performed to delineate the organ vasculature and performing various measurements, such as determining the diameter of the artery and measuring the required flow reducing implant diameter, followed by placement of the selected flow reducing implant. An angiographic study allows clear visualization of the hypervascular tumor, which is further studied by means of superselective catheterization. After the flow reducing implant has been placed, and further measurements have optionally been performed, such as pressure studies and another angiographic visualization, the catheter is removed, and the patient undergoes standard post-arteriographic monitoring and recovery.

0290In an exemplary embodiment of the invention, the method described may be used concurrently with an intraarterial infusion of antineoplastic agents mixed, for example, with iodized oil (Lipiodol (R)), which has been extensively used in the treatment of large HCC tumors, or combined with PEI (Percutaneous ethanol injection). It is expected that alcohol diffusion be easier after the occurrence of the hypoxic/necrotic changes produced by the implant, thus allowing the intranodular injection of larger amounts of ethanol. Moreover, after arterial embolization, the normal washout of the injected ethanol is more difficult in the tumorous area, resulting in potential longer retention of the substance. Various pharmaceuticals may be discharged by the flow reducing implant itself, as known, for example in the art of stents. For example, the flow reducing implant may be coated with various pharmaceuticals or the flow reducing implant may include a dissolving portion or a reservoir.

0291It will be appreciated that the above described methods of deploying a flow reducing implant may be varied in many ways, including, changing the order of acts, which acts are performed more often and which less often, the type and order of tools used and/or the particular timing sequences used. Further, the location of various elements may be switched, without exceeding the sprit of the disclosure. In addition, a multiplicity of features, both of methods and of implants have been described. It should be appreciated that different features may be combined in different ways. In particular, not all the features shown above in a particular embodiment are necessary in every similar exemplary embodiment of the invention. Further, combinations of features from different embodiments into a single embodiment or a single feature are also considered to be within the scope of some exemplary embodiments of the invention. In addition, some of the features of the invention described herein may be adapted for use with prior art devices, in accordance with other exemplary embodiments of the invention. The particular geometric forms and measurements used to illustrate the invention should not be considered limiting the invention in its broadest aspect to only those forms. Although some limitations are described only as method or apparatus limitations, the scope of the invention also includes apparatus designed to carry out the methods and methods of using the apparatus.

0292Also within the scope of the invention are surgical kits, for example, kits that include sets of delivery systems and flow reducing implants. Optionally, such kits also include instructions for use. Measurements are provided to serve only as exemplary measurements for particular cases, the exact measurements applied will vary depending on the application. When used in the following claims, the terms “comprises”, “comprising”, “includes”, “including” or the like means “including but not limited to”.

0293It will be appreciated by a person skilled in the art that the present invention is not limited by what has thus far been described. Rather, the scope of the present invention is limited only by the following claims.